diff --git a/.editorconfig b/.editorconfig
index ba2e60bb3..8c7b20388 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -513,6 +513,12 @@ ij_json_spaces_within_braces = false
 ij_json_spaces_within_brackets = false
 ij_json_wrap_long_lines = false
 
+# Weblate writes translation files with 4-space indent. Match that to avoid
+# whole-file reformat diffs when an editor saves them.
+[public/locales/**/*.json]
+indent_size = 4
+tab_width = 4
+
 [{*.htm,*.html,*.ng,*.sht,*.shtm,*.shtml}]
 ij_continuation_indent_size = 4
 ij_html_add_new_line_before_tags = body, div, p, form, h1, h2, h3
diff --git a/src/components/Calendar/Components/CalendarComponent.test.tsx b/src/components/Calendar/Components/CalendarComponent.test.tsx
index 9cebe159f..48a925082 100644
--- a/src/components/Calendar/Components/CalendarComponent.test.tsx
+++ b/src/components/Calendar/Components/CalendarComponent.test.tsx
@@ -51,10 +51,14 @@ describe('CalendarComponent', () => {
 
         (getMeasurementCategories as Mock).mockImplementation(() => Promise.resolve([
             new MeasurementCategory(
-                1,
+                'cccccccc-cccc-cccc-cccc-000000000001',
                 "Body Fat",
                 "%",
-                [new MeasurementEntry(1, 1, new Date(currentYear, currentMonth, 1, 12, 0), 20, "Normal")]
+                [new MeasurementEntry(
+                    'dddddddd-dddd-dddd-dddd-000000000001',
+                    'cccccccc-cccc-cccc-cccc-000000000001',
+                    new Date(currentYear, currentMonth, 1, 12, 0), 20, "Normal"
+                )]
             ),
         ]));
 
diff --git a/src/components/Dashboard/NutritionCard.tsx b/src/components/Dashboard/NutritionCard.tsx
index ffddd9c7e..7adcfe72e 100644
--- a/src/components/Dashboard/NutritionCard.tsx
+++ b/src/components/Dashboard/NutritionCard.tsx
@@ -103,7 +103,7 @@ function NutritionCardContent(props: { plan: NutritionalPlan }) {
     );
 }
 
-const MealListItem = (props: { meal: Meal; planId: number }) => {
+const MealListItem = (props: { meal: Meal; planId: string }) => {
     const [t, i18n] = useTranslation();
     const addDiaryEntryQuery = useAddDiaryEntryQuery(props.planId);
 
diff --git a/src/components/Exercises/api/exerciseTranslation.test.ts b/src/components/Exercises/api/exerciseTranslation.test.ts
index 7cf6f4007..85670268c 100644
--- a/src/components/Exercises/api/exerciseTranslation.test.ts
+++ b/src/components/Exercises/api/exerciseTranslation.test.ts
@@ -18,7 +18,6 @@ describe("Exercise translation service API tests", () => {
     });
 
 
-
     test('POST a new exercise translation', async () => {
 
         // Arrange
@@ -122,10 +121,10 @@ describe("Exercise translation service API tests", () => {
                     name: "Squats",
                     description: "Do a squat",
                     notes: [],
-                    creation_date: "2022-06-23",  
+                    creation_date: "2022-06-23",
                     language: 2,
                     license: 2,
-                    author_history: ["tester"],  
+                    author_history: ["tester"],
                 },
             ],
         };
diff --git a/src/components/Measurements/api/measurements.test.ts b/src/components/Measurements/api/measurements.test.ts
index 913f7f58b..d68606e23 100644
--- a/src/components/Measurements/api/measurements.test.ts
+++ b/src/components/Measurements/api/measurements.test.ts
@@ -15,6 +15,12 @@ import type { Mock } from 'vitest';
 
 vi.mock("axios");
 
+// Recognisable test-marker UUIDs matching the Django fixtures convention
+const CATEGORY_UUID = 'cccccccc-cccc-cccc-cccc-000000000001';
+const CATEGORY_UUID_2 = 'cccccccc-cccc-cccc-cccc-000000000009';
+const ENTRY_UUID = 'dddddddd-dddd-dddd-dddd-000000000001';
+const ENTRY_UUID_2 = 'dddddddd-dddd-dddd-dddd-000000000005';
+
 describe('measurement service tests', () => {
     const measurementEntryResponse = {
         count: 2,
@@ -22,8 +28,8 @@ describe('measurement service tests', () => {
         previous: null,
         results: [
             {
-                "id": 1,
-                "category": 1,
+                "id": ENTRY_UUID,
+                "category": CATEGORY_UUID,
                 "value": 80,
                 "date": "2021-01-01",
                 "notes": ""
@@ -37,7 +43,7 @@ describe('measurement service tests', () => {
         previous: null,
         results: [
             {
-                "id": 1,
+                "id": CATEGORY_UUID,
                 "name": "Weight",
                 "unit": "kg"
             }
@@ -45,7 +51,7 @@ describe('measurement service tests', () => {
     };
 
     const measurementDetailResponse = {
-        "id": 1,
+        "id": CATEGORY_UUID,
         "name": "Weight",
         "unit": "kg"
     };
@@ -57,7 +63,7 @@ describe('measurement service tests', () => {
         (axios.get as Mock).mockImplementation((url: string) => {
             if (url.includes("measurement-category")) {
                 return Promise.resolve({ data: measurementOverviewResponse });
-            } else if (url.includes("measurement/?category=1")) {
+            } else if (url.includes(`measurement/?category=${CATEGORY_UUID}`)) {
                 return Promise.resolve({ data: measurementEntryResponse });
             }
         });
@@ -88,8 +94,8 @@ describe('measurement service tests', () => {
         expect(axios.get).toHaveBeenCalledTimes(2);
 
         expect(result).toStrictEqual([
-            new MeasurementCategory(1, "Weight", "kg", [
-                new MeasurementEntry(1, 1, new Date("2021-01-01"), 80, "")
+            new MeasurementCategory(CATEGORY_UUID, "Weight", "kg", [
+                new MeasurementEntry(ENTRY_UUID, CATEGORY_UUID, new Date("2021-01-01"), 80, "")
             ])
         ]);
     });
@@ -97,26 +103,26 @@ describe('measurement service tests', () => {
     test('GET measurement category', async () => {
 
         (axios.get as Mock).mockImplementation((url: string) => {
-            if (url.includes("measurement-category/1")) {
+            if (url.includes(`measurement-category/${CATEGORY_UUID}`)) {
                 return Promise.resolve({ data: measurementDetailResponse });
-            } else if (url.includes("measurement/?category=1")) {
+            } else if (url.includes(`measurement/?category=${CATEGORY_UUID}`)) {
                 return Promise.resolve({ data: measurementEntryResponse });
             }
         });
 
-        const result = await getMeasurementCategory(1);
+        const result = await getMeasurementCategory(CATEGORY_UUID);
         expect(axios.get).toHaveBeenCalledTimes(2);
 
         expect(result).toStrictEqual(
-            new MeasurementCategory(1, "Weight", "kg", [
-                new MeasurementEntry(1, 1, new Date("2021-01-01"), 80, "")
+            new MeasurementCategory(CATEGORY_UUID, "Weight", "kg", [
+                new MeasurementEntry(ENTRY_UUID, CATEGORY_UUID, new Date("2021-01-01"), 80, "")
             ])
         );
     });
 
     test('addMeasurementCategory POSTs name + unit and returns the parsed category', async () => {
         (axios.post as Mock).mockResolvedValue({
-            data: { id: 9, name: "Body fat", unit: "%" },
+            data: { id: CATEGORY_UUID_2, name: "Body fat", unit: "%" },
         });
 
         const result = await addMeasurementCategory({ name: "Body fat", unit: "%" });
@@ -126,19 +132,19 @@ describe('measurement service tests', () => {
         expect(url).toMatch(/\/api\/v2\/measurement-category\/$/);
         expect(body).toEqual({ name: "Body fat", unit: "%" });
         expect(result).toBeInstanceOf(MeasurementCategory);
-        expect(result.id).toBe(9);
+        expect(result.id).toBe(CATEGORY_UUID_2);
     });
 
     test('editMeasurementCategory PATCHes /measurement-category/<id>/', async () => {
         (axios.patch as Mock).mockResolvedValue({
-            data: { id: 9, name: "Renamed", unit: "%" },
+            data: { id: CATEGORY_UUID_2, name: "Renamed", unit: "%" },
         });
 
-        const result = await editMeasurementCategory({ id: 9, name: "Renamed", unit: "%" });
+        const result = await editMeasurementCategory({ id: CATEGORY_UUID_2, name: "Renamed", unit: "%" });
 
         expect(axios.patch).toHaveBeenCalledTimes(1);
         const [url, body] = (axios.patch as Mock).mock.calls[0];
-        expect(url).toMatch(/\/api\/v2\/measurement-category\/9\/$/);
+        expect(url).toMatch(new RegExp(`/api/v2/measurement-category/${CATEGORY_UUID_2}/$`));
         expect(body).toEqual({ name: "Renamed", unit: "%" });
         expect(result.name).toBe("Renamed");
     });
@@ -146,21 +152,21 @@ describe('measurement service tests', () => {
     test('deleteMeasurementCategory DELETEs /measurement-category/<id>/', async () => {
         (axios.delete as Mock).mockResolvedValue({ status: 204 });
 
-        await deleteMeasurementCategory(9);
+        await deleteMeasurementCategory(CATEGORY_UUID_2);
 
         expect(axios.delete).toHaveBeenCalledWith(
-            expect.stringMatching(/\/api\/v2\/measurement-category\/9\/$/),
+            expect.stringMatching(new RegExp(`/api/v2/measurement-category/${CATEGORY_UUID_2}/$`)),
             expect.anything()
         );
     });
 
     test('addMeasurementEntry POSTs the entry with serialized date', async () => {
         (axios.post as Mock).mockResolvedValue({
-            data: { id: 5, category: 1, value: 80.5, date: "2024-08-01", notes: "" },
+            data: { id: ENTRY_UUID_2, category: CATEGORY_UUID, value: 80.5, date: "2024-08-01", notes: "" },
         });
 
         const result = await addMeasurementEntry({
-            categoryId: 1,
+            categoryId: CATEGORY_UUID,
             date: new Date("2024-08-01T12:34:00Z"),
             value: 80.5,
             notes: "",
@@ -170,24 +176,24 @@ describe('measurement service tests', () => {
         const [url, body] = (axios.post as Mock).mock.calls[0];
         expect(url).toMatch(/\/api\/v2\/measurement\/$/);
         expect(body).toMatchObject({
-            category: 1,
+            category: CATEGORY_UUID,
             value: 80.5,
             notes: "",
         });
         // Date is YYYY-MM-DD
         expect(body.date).toMatch(/^\d{4}-\d{2}-\d{2}$/);
         expect(result).toBeInstanceOf(MeasurementEntry);
-        expect(result.id).toBe(5);
+        expect(result.id).toBe(ENTRY_UUID_2);
     });
 
     test('editMeasurementEntry PATCHes /measurement/<id>/ with date/value/notes only', async () => {
         (axios.patch as Mock).mockResolvedValue({
-            data: { id: 5, category: 1, value: 81, date: "2024-08-02", notes: "edited" },
+            data: { id: ENTRY_UUID_2, category: CATEGORY_UUID, value: 81, date: "2024-08-02", notes: "edited" },
         });
 
         const result = await editMeasurementEntry({
-            id: 5,
-            categoryId: 1,
+            id: ENTRY_UUID_2,
+            categoryId: CATEGORY_UUID,
             date: new Date("2024-08-02T00:00:00Z"),
             value: 81,
             notes: "edited",
@@ -195,7 +201,7 @@ describe('measurement service tests', () => {
 
         expect(axios.patch).toHaveBeenCalledTimes(1);
         const [url, body] = (axios.patch as Mock).mock.calls[0];
-        expect(url).toMatch(/\/api\/v2\/measurement\/5\/$/);
+        expect(url).toMatch(new RegExp(`/api/v2/measurement/${ENTRY_UUID_2}/$`));
         // Note: 'category' is NOT sent on edit (categoryId is part of the params but ignored in body)
         expect(body).not.toHaveProperty("category");
         expect(body).toMatchObject({ value: 81, notes: "edited" });
@@ -206,10 +212,10 @@ describe('measurement service tests', () => {
     test('deleteMeasurementEntry DELETEs /measurement/<id>/', async () => {
         (axios.delete as Mock).mockResolvedValue({ status: 204 });
 
-        await deleteMeasurementEntry(5);
+        await deleteMeasurementEntry(ENTRY_UUID_2);
 
         expect(axios.delete).toHaveBeenCalledWith(
-            expect.stringMatching(/\/api\/v2\/measurement\/5\/$/),
+            expect.stringMatching(new RegExp(`/api/v2/measurement/${ENTRY_UUID_2}/$`)),
             expect.anything()
         );
     });
diff --git a/src/components/Measurements/api/measurements.ts b/src/components/Measurements/api/measurements.ts
index 515915b1e..b39dd0894 100644
--- a/src/components/Measurements/api/measurements.ts
+++ b/src/components/Measurements/api/measurements.ts
@@ -54,7 +54,7 @@ export const getMeasurementCategories = async (options?: MeasurementQueryOptions
     const settingsResponses = await Promise.all(entryResponses);
 
     // Save entries to each category
-    let categoryId: number;
+    let categoryId: string;
     settingsResponses.forEach((entries) => {
         if (entries.length > 0) {
             categoryId = entries[0].category;
@@ -65,7 +65,7 @@ export const getMeasurementCategories = async (options?: MeasurementQueryOptions
     return categories;
 };
 
-export const getMeasurementCategory = async (id: number): Promise<MeasurementCategory> => {
+export const getMeasurementCategory = async (id: string): Promise<MeasurementCategory> => {
     const { data: receivedCategories } = await axios.get<ApiMeasurementCategoryType>(
         makeUrl(API_MEASUREMENTS_CATEGORY_PATH, { id: id }),
         { headers: makeHeader() },
@@ -106,7 +106,7 @@ export const addMeasurementCategory = async (data: AddMeasurementCategoryParams)
 };
 
 export interface editMeasurementCategoryParams {
-    id: number,
+    id: string,
     name: string;
     unit: string;
 }
@@ -124,18 +124,18 @@ export const editMeasurementCategory = async (data: editMeasurementCategoryParam
     return MeasurementCategory.fromJson(response.data);
 };
 
-export const deleteMeasurementCategory = async (id: number): Promise<void> => {
+export const deleteMeasurementCategory = async (id: string): Promise<void> => {
     await axios.delete(makeUrl(API_MEASUREMENTS_CATEGORY_PATH, { id: id }), { headers: makeHeader() });
 };
 
 
-export const deleteMeasurementEntry = async (id: number): Promise<void> => {
+export const deleteMeasurementEntry = async (id: string): Promise<void> => {
     await axios.delete(makeUrl(API_MEASUREMENTS_ENTRY_PATH, { id: id }), { headers: makeHeader() });
 };
 
 export interface editMeasurementParams {
-    id: number,
-    categoryId?: number,
+    id: string,
+    categoryId?: string,
     date: Date;
     value: number;
     notes: string;
@@ -156,7 +156,7 @@ export const editMeasurementEntry = async (data: editMeasurementParams): Promise
 };
 
 export interface AddMeasurementParams {
-    categoryId: number;
+    categoryId: string;
     date: Date;
     value: number;
     notes: string;
diff --git a/src/components/Measurements/models/Category.ts b/src/components/Measurements/models/Category.ts
index 08861e1b3..9af75e341 100644
--- a/src/components/Measurements/models/Category.ts
+++ b/src/components/Measurements/models/Category.ts
@@ -6,7 +6,7 @@ export class MeasurementCategory {
     entries: MeasurementEntry[] = [];
 
     constructor(
-        public id: number,
+        public id: string,
         public name: string,
         public unit: string,
         entries?: MeasurementEntry[]
diff --git a/src/components/Measurements/models/Entry.ts b/src/components/Measurements/models/Entry.ts
index d2a23a9d3..5a095499e 100644
--- a/src/components/Measurements/models/Entry.ts
+++ b/src/components/Measurements/models/Entry.ts
@@ -3,8 +3,8 @@ import { Adapter } from "@/core/lib/Adapter";
 export class MeasurementEntry {
 
     constructor(
-        public id: number | null,
-        public category: number,
+        public id: string | null,
+        public category: string,
         public date: Date,
         public value: number,
         public notes: string
diff --git a/src/components/Measurements/queries/index.ts b/src/components/Measurements/queries/index.ts
index f958c16fb..9b30de8a1 100644
--- a/src/components/Measurements/queries/index.ts
+++ b/src/components/Measurements/queries/index.ts
@@ -35,7 +35,7 @@ export const useAddMeasurementCategoryQuery = () => {
     });
 };
 
-export const useEditMeasurementCategoryQuery = (id: number) => {
+export const useEditMeasurementCategoryQuery = (id: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
@@ -51,11 +51,11 @@ export const useEditMeasurementCategoryQuery = (id: number) => {
     });
 };
 
-export const useDeleteMeasurementCategoryQuery = (id: number) => {
+export const useDeleteMeasurementCategoryQuery = (id: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
-        mutationFn: (id: number) => deleteMeasurementCategory(id),
+        mutationFn: (id: string) => deleteMeasurementCategory(id),
         onSuccess: () => {
             queryClient.invalidateQueries({
                 queryKey: [QueryKey.MEASUREMENTS, id]
@@ -68,7 +68,7 @@ export const useDeleteMeasurementCategoryQuery = (id: number) => {
 };
 
 
-export function useMeasurementsQuery(id: number) {
+export function useMeasurementsQuery(id: string) {
     return useQuery({
         queryKey: [QueryKey.MEASUREMENTS, id],
         queryFn: () => getMeasurementCategory(id)
@@ -111,7 +111,7 @@ export const useDeleteMeasurementsQuery = (/*id: number*/) => {
     const queryClient = useQueryClient();
 
     return useMutation({
-        mutationFn: (id: number) => deleteMeasurementEntry(id),
+        mutationFn: (id: string) => deleteMeasurementEntry(id),
         onSuccess: () => queryClient.invalidateQueries({
             queryKey: [QueryKey.MEASUREMENTS,]
         })
diff --git a/src/components/Measurements/screens/MeasurementCategoryDetail.tsx b/src/components/Measurements/screens/MeasurementCategoryDetail.tsx
index 64dff3749..14d32509f 100644
--- a/src/components/Measurements/screens/MeasurementCategoryDetail.tsx
+++ b/src/components/Measurements/screens/MeasurementCategoryDetail.tsx
@@ -11,9 +11,9 @@ import { useParams } from "react-router-dom";
 
 export const MeasurementCategoryDetail = () => {
     const params = useParams<{ categoryId: string }>();
-    const categoryId = parseInt(params.categoryId ?? '');
-    if (Number.isNaN(categoryId)) {
-        return <p>Please pass an integer as the category id.</p>;
+    const categoryId = params.categoryId ?? '';
+    if (!categoryId) {
+        return <p>Please pass a category id.</p>;
     }
 
     // eslint-disable-next-line react-hooks/rules-of-hooks
diff --git a/src/components/Measurements/widgets/CategoryDetailDataGrid.tsx b/src/components/Measurements/widgets/CategoryDetailDataGrid.tsx
index 6a4d5bec8..8de749a22 100644
--- a/src/components/Measurements/widgets/CategoryDetailDataGrid.tsx
+++ b/src/components/Measurements/widgets/CategoryDetailDataGrid.tsx
@@ -61,7 +61,7 @@ export const CategoryDetailDataGrid = (props: { category: MeasurementCategory })
     };
 
     const handleDeleteClick = (id: GridRowId) => async () => {
-        deleteEntryQuery.mutate(parseInt(id.toString()));
+        deleteEntryQuery.mutate(id.toString());
     };
 
     const handleCancelClick = (id: GridRowId) => () => {
diff --git a/src/components/Measurements/widgets/CategoryForm.test.tsx b/src/components/Measurements/widgets/CategoryForm.test.tsx
index c8a53f581..907062bd2 100644
--- a/src/components/Measurements/widgets/CategoryForm.test.tsx
+++ b/src/components/Measurements/widgets/CategoryForm.test.tsx
@@ -65,7 +65,7 @@ describe("Test the CategoryForm component", () => {
         // Assert
         await user.click(submitButton);
         expect(mutate).toHaveBeenCalledWith({
-            id: 2,
+            id: 'cccccccc-cccc-cccc-cccc-000000000002',
             name: "a better name",
             unit: 'K/m2',
         });
diff --git a/src/components/Measurements/widgets/CategoryForm.tsx b/src/components/Measurements/widgets/CategoryForm.tsx
index 0d0352660..e94c089b4 100644
--- a/src/components/Measurements/widgets/CategoryForm.tsx
+++ b/src/components/Measurements/widgets/CategoryForm.tsx
@@ -15,7 +15,7 @@ export const CategoryForm = ({ category, closeFn }: CategoryFormProps) => {
 
     const [t] = useTranslation();
     const useAddCategoryQuery = useAddMeasurementCategoryQuery();
-    const useEditCategoryQuery = useEditMeasurementCategoryQuery(category?.id || 0);
+    const useEditCategoryQuery = useEditMeasurementCategoryQuery(category?.id || '');
     // Match the backend column limits. We do NOT enforce a minimum length:
     // many users have legitimate 1-2 char names (e.g. CJK abbreviations
     // like 体重 / 体脂), and the backend allows them.
diff --git a/src/components/Measurements/widgets/EntryForm.test.tsx b/src/components/Measurements/widgets/EntryForm.test.tsx
index 971dbb902..747722e04 100644
--- a/src/components/Measurements/widgets/EntryForm.test.tsx
+++ b/src/components/Measurements/widgets/EntryForm.test.tsx
@@ -25,7 +25,7 @@ describe("Test the EntryForm component", () => {
     const queryClient = new QueryClient();
     let mutate = vi.fn();
 
-    const renderComponent = (props: { entry?: MeasurementEntry, categoryId: number }) => {
+    const renderComponent = (props: { entry?: MeasurementEntry, categoryId: string }) => {
         return render(
             <QueryClientProvider client={queryClient}>
                 <EntryForm {...props} />
@@ -56,7 +56,7 @@ describe("Test the EntryForm component", () => {
         const entry = TEST_MEASUREMENT_ENTRIES_1[0];
 
         // Act
-        renderComponent({ entry, categoryId: 1 });
+        renderComponent({ entry, categoryId: 'cccccccc-cccc-cccc-cccc-000000000001' });
 
         // Assert
         expect(screen.getByDisplayValue('10')).toBeInTheDocument();
@@ -74,7 +74,7 @@ describe("Test the EntryForm component", () => {
         const user = userEvent.setup();
 
         // Act
-        renderComponent({ entry, categoryId: 1 });
+        renderComponent({ entry, categoryId: 'cccccccc-cccc-cccc-cccc-000000000001' });
         const submitButton = screen.getByRole('button', { name: 'submit' });
         await user.clear(screen.getByLabelText('value'));
         await user.type(screen.getByLabelText('value'), '25');
@@ -84,7 +84,7 @@ describe("Test the EntryForm component", () => {
         await user.click(submitButton);
         expect(mutate).toHaveBeenCalledWith({
             date: expect.anything(),
-            id: 1,
+            id: 'dddddddd-dddd-dddd-dddd-000000000001',
             notes: "test note",
             value: 25,
         });
@@ -97,7 +97,7 @@ describe("Test the EntryForm component", () => {
         const user = userEvent.setup({ advanceTimers: vi.advanceTimersByTime });
 
         // Act
-        renderComponent({ categoryId: 11 });
+        renderComponent({ categoryId: 'cccccccc-cccc-cccc-cccc-000000000011' });
         const valueInput = await screen.findByLabelText('value');
         const notesInput = await screen.findByLabelText('notes');
         const submitButton = screen.getByRole('button', { name: 'submit' });
@@ -111,7 +111,7 @@ describe("Test the EntryForm component", () => {
         expect(submitButton).toBeInTheDocument();
         await user.click(submitButton);
         expect(mutate).toHaveBeenCalledWith({
-            categoryId: 11,
+            categoryId: 'cccccccc-cccc-cccc-cccc-000000000011',
             date: fakeNow,
             notes: 'The Shiba Inu is a breed of hunting dog from Japan.',
             value: 42.42,
@@ -129,7 +129,7 @@ describe("Test the EntryForm component", () => {
             i18n.changeLanguage('en');
             const entry = TEST_MEASUREMENT_ENTRIES_1[0];
 
-            const { container } = renderComponent({ entry, categoryId: 1 });
+            const { container } = renderComponent({ entry, categoryId: 'cccccccc-cccc-cccc-cccc-000000000001' });
 
             const picker = container.querySelector('.MuiPickersInputBase-root');
             expect(picker?.textContent).toContain('02/01/2023');
@@ -140,7 +140,7 @@ describe("Test the EntryForm component", () => {
             i18n.changeLanguage('de');
             const entry = TEST_MEASUREMENT_ENTRIES_1[0];
 
-            const { container } = renderComponent({ entry, categoryId: 1 });
+            const { container } = renderComponent({ entry, categoryId: 'cccccccc-cccc-cccc-cccc-000000000001' });
 
             const picker = container.querySelector('.MuiPickersInputBase-root');
             expect(picker?.textContent).toContain('01.02.2023');
diff --git a/src/components/Measurements/widgets/EntryForm.tsx b/src/components/Measurements/widgets/EntryForm.tsx
index a892cb311..2b4c10c62 100644
--- a/src/components/Measurements/widgets/EntryForm.tsx
+++ b/src/components/Measurements/widgets/EntryForm.tsx
@@ -20,7 +20,7 @@ Settings.defaultZone = TIMEZONE;
 interface EntryFormProps {
     entry?: MeasurementEntry,
     closeFn?: () => void,
-    categoryId: number,
+    categoryId: string,
 }
 
 export const EntryForm = ({ entry, closeFn, categoryId }: EntryFormProps) => {
diff --git a/src/components/Measurements/widgets/fab.tsx b/src/components/Measurements/widgets/fab.tsx
index 79e6a7ef6..4f6f04494 100644
--- a/src/components/Measurements/widgets/fab.tsx
+++ b/src/components/Measurements/widgets/fab.tsx
@@ -42,7 +42,7 @@ export const AddMeasurementEntryFab = () => {
     const handleCloseModal = () => setOpenModal(false);
 
     const params = useParams<{ categoryId: string }>();
-    const categoryId = parseInt(params.categoryId!);
+    const categoryId = params.categoryId!;
 
 
     return (<>
diff --git a/src/components/Nutrition/api/meal.test.ts b/src/components/Nutrition/api/meal.test.ts
index e17aeae3c..abe817cbf 100644
--- a/src/components/Nutrition/api/meal.test.ts
+++ b/src/components/Nutrition/api/meal.test.ts
@@ -1,14 +1,16 @@
-import axios from "axios";
-import { Meal } from "@/components/Nutrition/models/meal";
-import { addMeal, deleteMeal, editMeal, getMealsForPlan } from "@/components/Nutrition/api/meal";
 import { getIngredients } from "@/components/Nutrition/api/ingredient";
+import { addMeal, deleteMeal, editMeal, getMealsForPlan } from "@/components/Nutrition/api/meal";
+import { Meal } from "@/components/Nutrition/models/meal";
+import { HHMMToDateTime } from "@/core/lib/date";
+import { TEST_INGREDIENT_1, TEST_INGREDIENT_2 } from "@/tests/ingredientTestdata";
 import {
+    RESPONSE_MEAL_UUID,
+    RESPONSE_PLAN_UUID_2,
     responseMealDetail,
     responseMealItemsForMeal,
     responseMealsForPlan,
 } from "@/tests/nutritionTestdata";
-import { TEST_INGREDIENT_1, TEST_INGREDIENT_2 } from "@/tests/ingredientTestdata";
-import { HHMMToDateTime } from "@/core/lib/date";
+import axios from "axios";
 import type { Mock } from "vitest";
 
 vi.mock("axios");
@@ -20,7 +22,12 @@ describe("meal service tests", () => {
     });
 
     test("addMeal POSTs the serialized meal and returns the parsed Meal", async () => {
-        const meal = new Meal({ planId: 123, order: 2, time: HHMMToDateTime("12:30"), name: "Second breakfast" });
+        const meal = new Meal({
+            planId: RESPONSE_PLAN_UUID_2,
+            order: 2,
+            time: HHMMToDateTime("12:30"),
+            name: "Second breakfast"
+        });
         (axios.post as Mock).mockResolvedValue({ data: responseMealDetail });
 
         const result = await addMeal(meal);
@@ -28,34 +35,40 @@ describe("meal service tests", () => {
         expect(axios.post).toHaveBeenCalledTimes(1);
         const [url, body] = (axios.post as Mock).mock.calls[0];
         expect(url).toMatch(/\/api\/v2\/meal\/$/);
-        expect(body).toMatchObject({ plan: 123, name: "Second breakfast", order: 2, time: "12:30" });
+        expect(body).toMatchObject({ plan: RESPONSE_PLAN_UUID_2, name: "Second breakfast", order: 2, time: "12:30" });
         // toJson omits the id field when it's null - verify
         expect(body).not.toHaveProperty("id");
         expect(result).toBeInstanceOf(Meal);
-        expect(result.id).toBe(78);
+        expect(result.id).toBe(RESPONSE_MEAL_UUID);
     });
 
     test("editMeal PATCHes /meal/<id>/ and returns the parsed Meal", async () => {
-        const meal = new Meal({ id: 78, planId: 123, order: 2, time: HHMMToDateTime("12:30"), name: "renamed" });
+        const meal = new Meal({
+            id: RESPONSE_MEAL_UUID,
+            planId: RESPONSE_PLAN_UUID_2,
+            order: 2,
+            time: HHMMToDateTime("12:30"),
+            name: "renamed"
+        });
         (axios.patch as Mock).mockResolvedValue({ data: { ...responseMealDetail, name: "renamed" } });
 
         const result = await editMeal(meal);
 
         expect(axios.patch).toHaveBeenCalledTimes(1);
         const [url, body] = (axios.patch as Mock).mock.calls[0];
-        expect(url).toMatch(/\/api\/v2\/meal\/78\/$/);
-        expect(body).toMatchObject({ id: 78, name: "renamed" });
+        expect(url).toMatch(new RegExp(`/api/v2/meal/${RESPONSE_MEAL_UUID}/$`));
+        expect(body).toMatchObject({ id: RESPONSE_MEAL_UUID, name: "renamed" });
         expect(result.name).toBe("renamed");
     });
 
     test("deleteMeal DELETEs /meal/<id>/", async () => {
         (axios.delete as Mock).mockResolvedValue({ status: 204 });
 
-        await deleteMeal(78);
+        await deleteMeal(RESPONSE_MEAL_UUID);
 
         expect(axios.delete).toHaveBeenCalledTimes(1);
         expect(axios.delete).toHaveBeenCalledWith(
-            expect.stringMatching(/\/api\/v2\/meal\/78\/$/),
+            expect.stringMatching(new RegExp(`/api/v2/meal/${RESPONSE_MEAL_UUID}/$`)),
             expect.anything()
         );
     });
@@ -70,12 +83,12 @@ describe("meal service tests", () => {
         });
         (getIngredients as Mock).mockResolvedValue([TEST_INGREDIENT_1, TEST_INGREDIENT_2]);
 
-        const result = await getMealsForPlan(123);
+        const result = await getMealsForPlan(RESPONSE_PLAN_UUID_2);
 
         // The list call filters by plan, the item call filters by meal
         const calledUrls = (axios.get as Mock).mock.calls.map(([u]) => u as string);
-        expect(calledUrls.some(u => u.includes("/meal/?plan=123"))).toBe(true);
-        expect(calledUrls.some(u => u.includes("/mealitem/?meal=78"))).toBe(true);
+        expect(calledUrls.some(u => u.includes(`/meal/?plan=${RESPONSE_PLAN_UUID_2}`))).toBe(true);
+        expect(calledUrls.some(u => u.includes(`/mealitem/?meal=${RESPONSE_MEAL_UUID}`))).toBe(true);
 
         // getIngredients is called once per meal with the deduped ingredient ids
         expect(getIngredients).toHaveBeenCalledWith([101, 102]);
@@ -95,7 +108,7 @@ describe("meal service tests", () => {
             data: { count: 0, next: null, previous: null, results: [] },
         });
 
-        const result = await getMealsForPlan(123);
+        const result = await getMealsForPlan(RESPONSE_PLAN_UUID_2);
 
         expect(result).toEqual([]);
         // No item calls, no ingredient lookups
diff --git a/src/components/Nutrition/api/meal.ts b/src/components/Nutrition/api/meal.ts
index bce3ec163..78d63ee46 100644
--- a/src/components/Nutrition/api/meal.ts
+++ b/src/components/Nutrition/api/meal.ts
@@ -27,14 +27,14 @@ export const editMeal = async (meal: Meal): Promise<Meal> => {
     return Meal.fromJson(response.data);
 };
 
-export const deleteMeal = async (id: number): Promise<void> => {
+export const deleteMeal = async (id: string): Promise<void> => {
     await axios.delete(
         makeUrl(ApiPath.MEAL, { id: id }),
         { headers: makeHeader() },
     );
 };
 
-export const getMealsForPlan = async (planId: number): Promise<Meal[]> => {
+export const getMealsForPlan = async (planId: string): Promise<Meal[]> => {
 
     let ingredientIds: number[] = [];
     const { data: receivedMeals } = await axios.get<ResponseType<ApiMealType>>(
diff --git a/src/components/Nutrition/api/mealItem.test.ts b/src/components/Nutrition/api/mealItem.test.ts
index ff3833d4e..24cd4f93d 100644
--- a/src/components/Nutrition/api/mealItem.test.ts
+++ b/src/components/Nutrition/api/mealItem.test.ts
@@ -1,6 +1,6 @@
 import { addMealItem, deleteMealItem, editMealItem } from "@/components/Nutrition/api/mealItem";
 import { MealItem } from "@/components/Nutrition/models/mealItem";
-import { responseMealItemDetail } from "@/tests/nutritionTestdata";
+import { RESPONSE_MEAL_ITEM_UUID, RESPONSE_MEAL_UUID, responseMealItemDetail, } from "@/tests/nutritionTestdata";
 import axios from "axios";
 import type { Mock } from "vitest";
 
@@ -12,7 +12,13 @@ describe("mealItem service tests", () => {
     });
 
     test("addMealItem POSTs the serialized item and returns the parsed MealItem", async () => {
-        const item = new MealItem({ mealId: 78, ingredientId: 101, weightUnitId: null, amount: 120, order: 3 });
+        const item = new MealItem({
+            mealId: RESPONSE_MEAL_UUID,
+            ingredientId: 101,
+            weightUnitId: null,
+            amount: 120,
+            order: 3
+        });
         (axios.post as Mock).mockResolvedValue({ data: responseMealItemDetail });
 
         const result = await addMealItem(item);
@@ -21,7 +27,7 @@ describe("mealItem service tests", () => {
         const [url, body] = (axios.post as Mock).mock.calls[0];
         expect(url).toMatch(/\/api\/v2\/mealitem\/$/);
         expect(body).toMatchObject({
-            meal: 78,
+            meal: RESPONSE_MEAL_UUID,
             ingredient: 101,
 
             weight_unit: null,
@@ -30,29 +36,36 @@ describe("mealItem service tests", () => {
         });
         expect(body).not.toHaveProperty("id");
         expect(result).toBeInstanceOf(MealItem);
-        expect(result.id).toBe(42);
+        expect(result.id).toBe(RESPONSE_MEAL_ITEM_UUID);
     });
 
     test("editMealItem PATCHes /mealitem/<id>/", async () => {
-        const item = new MealItem({ id: 42, mealId: 78, ingredientId: 101, weightUnitId: null, amount: 99, order: 3 });
+        const item = new MealItem({
+            id: RESPONSE_MEAL_ITEM_UUID,
+            mealId: RESPONSE_MEAL_UUID,
+            ingredientId: 101,
+            weightUnitId: null,
+            amount: 99,
+            order: 3
+        });
         (axios.patch as Mock).mockResolvedValue({ data: { ...responseMealItemDetail, amount: "99.00" } });
 
         const result = await editMealItem(item);
 
         expect(axios.patch).toHaveBeenCalledTimes(1);
         const [url, body] = (axios.patch as Mock).mock.calls[0];
-        expect(url).toMatch(/\/api\/v2\/mealitem\/42\/$/);
-        expect(body).toMatchObject({ id: 42, amount: "99" });
+        expect(url).toMatch(new RegExp(`/api/v2/mealitem/${RESPONSE_MEAL_ITEM_UUID}/$`));
+        expect(body).toMatchObject({ id: RESPONSE_MEAL_ITEM_UUID, amount: "99" });
         expect(result.amount).toBe(99);
     });
 
     test("deleteMealItem DELETEs /mealitem/<id>/", async () => {
         (axios.delete as Mock).mockResolvedValue({ status: 204 });
 
-        await deleteMealItem(42);
+        await deleteMealItem(RESPONSE_MEAL_ITEM_UUID);
 
         expect(axios.delete).toHaveBeenCalledWith(
-            expect.stringMatching(/\/api\/v2\/mealitem\/42\/$/),
+            expect.stringMatching(new RegExp(`/api/v2/mealitem/${RESPONSE_MEAL_ITEM_UUID}/$`)),
             expect.anything()
         );
     });
diff --git a/src/components/Nutrition/api/mealItem.ts b/src/components/Nutrition/api/mealItem.ts
index 5815c2e6e..358305182 100644
--- a/src/components/Nutrition/api/mealItem.ts
+++ b/src/components/Nutrition/api/mealItem.ts
@@ -24,7 +24,7 @@ export const editMealItem = async (mealItem: MealItem): Promise<MealItem> => {
     return MealItem.fromJson(response.data);
 };
 
-export const deleteMealItem = async (id: number): Promise<void> => {
+export const deleteMealItem = async (id: string): Promise<void> => {
     await axios.delete(
         makeUrl(ApiPath.MEAL_ITEM, { id: id }),
         { headers: makeHeader() },
diff --git a/src/components/Nutrition/api/nutritionalDiary.test.ts b/src/components/Nutrition/api/nutritionalDiary.test.ts
index 339ef3164..ce109dd1e 100644
--- a/src/components/Nutrition/api/nutritionalDiary.test.ts
+++ b/src/components/Nutrition/api/nutritionalDiary.test.ts
@@ -7,7 +7,13 @@ import {
 } from "@/components/Nutrition/api/nutritionalDiary";
 import { DiaryEntry } from "@/components/Nutrition/models/diaryEntry";
 import { TEST_INGREDIENT_1 } from "@/tests/ingredientTestdata";
-import { responseDiaryEntries, responseDiaryEntryDetail } from "@/tests/nutritionTestdata";
+import {
+    RESPONSE_DIARY_UUID,
+    RESPONSE_MEAL_UUID,
+    RESPONSE_PLAN_UUID,
+    responseDiaryEntries,
+    responseDiaryEntryDetail,
+} from "@/tests/nutritionTestdata";
 import axios from "axios";
 import type { Mock } from 'vitest';
 
@@ -55,7 +61,7 @@ describe("Nutritional diary service tests", () => {
             count: 2,
             results: [
                 responseDiaryEntries.results[0],
-                { ...responseDiaryEntries.results[0], id: 10 },
+                { ...responseDiaryEntries.results[0], id: 'dddddddd-0000-0000-0000-000000000010' },
             ],
         };
         (axios.get as Mock).mockResolvedValue({ data: dupedEntries });
@@ -74,8 +80,8 @@ describe("Nutritional diary service tests", () => {
 
     test('addNutritionalDiaryEntry POSTs the serialized entry', async () => {
         const entry = new DiaryEntry({
-            planId: 101,
-            mealId: 78,
+            planId: RESPONSE_PLAN_UUID,
+            mealId: RESPONSE_MEAL_UUID,
             ingredientId: 101,
             weightUnitId: null,
             amount: 150,
@@ -89,8 +95,8 @@ describe("Nutritional diary service tests", () => {
         const [url, body] = (axios.post as Mock).mock.calls[0];
         expect(url).toMatch(/\/api\/v2\/nutritiondiary\/$/);
         expect(body).toMatchObject({
-            plan: 101,
-            meal: 78,
+            plan: RESPONSE_PLAN_UUID,
+            meal: RESPONSE_MEAL_UUID,
             ingredient: 101,
 
             weight_unit: null,
@@ -98,14 +104,14 @@ describe("Nutritional diary service tests", () => {
             datetime: "2024-08-01T08:00:00.000Z",
         });
         expect(result).toBeInstanceOf(DiaryEntry);
-        expect(result.id).toBe(9);
+        expect(result.id).toBe(RESPONSE_DIARY_UUID);
     });
 
     test('editNutritionalDiaryEntry PATCHes /nutritiondiary/<id>/', async () => {
         const entry = new DiaryEntry({
-            id: 9,
-            planId: 101,
-            mealId: 78,
+            id: RESPONSE_DIARY_UUID,
+            planId: RESPONSE_PLAN_UUID,
+            mealId: RESPONSE_MEAL_UUID,
             ingredientId: 101,
             weightUnitId: null,
             amount: 99,
@@ -119,7 +125,7 @@ describe("Nutritional diary service tests", () => {
 
         expect(axios.patch).toHaveBeenCalledTimes(1);
         const [url, body] = (axios.patch as Mock).mock.calls[0];
-        expect(url).toMatch(/\/api\/v2\/nutritiondiary\/9\/$/);
+        expect(url).toMatch(new RegExp(`/api/v2/nutritiondiary/${RESPONSE_DIARY_UUID}/$`));
         expect(body).toMatchObject({ amount: "99" });
         expect(result.amount).toBe(99);
     });
@@ -127,10 +133,10 @@ describe("Nutritional diary service tests", () => {
     test('deleteNutritionalDiaryEntry DELETEs /nutritiondiary/<id>/', async () => {
         (axios.delete as Mock).mockResolvedValue({ status: 204 });
 
-        await deleteNutritionalDiaryEntry(9);
+        await deleteNutritionalDiaryEntry(RESPONSE_DIARY_UUID);
 
         expect(axios.delete).toHaveBeenCalledWith(
-            expect.stringMatching(/\/api\/v2\/nutritiondiary\/9\/$/),
+            expect.stringMatching(new RegExp(`/api/v2/nutritiondiary/${RESPONSE_DIARY_UUID}/$`)),
             expect.anything()
         );
     });
diff --git a/src/components/Nutrition/api/nutritionalDiary.ts b/src/components/Nutrition/api/nutritionalDiary.ts
index 88593afdc..5cba5d0d5 100644
--- a/src/components/Nutrition/api/nutritionalDiary.ts
+++ b/src/components/Nutrition/api/nutritionalDiary.ts
@@ -67,7 +67,7 @@ export const editNutritionalDiaryEntry = async (diaryEntry: DiaryEntry): Promise
     return DiaryEntry.fromJson(response.data);
 };
 
-export const deleteNutritionalDiaryEntry = async (id: number): Promise<void> => {
+export const deleteNutritionalDiaryEntry = async (id: string): Promise<void> => {
     await axios.delete(
         makeUrl(ApiPath.NUTRITIONAL_DIARY, { id: id }),
         { headers: makeHeader() },
diff --git a/src/components/Nutrition/api/nutritionalPlan.test.ts b/src/components/Nutrition/api/nutritionalPlan.test.ts
index 12e226bf7..12f8e6d30 100644
--- a/src/components/Nutrition/api/nutritionalPlan.test.ts
+++ b/src/components/Nutrition/api/nutritionalPlan.test.ts
@@ -10,6 +10,8 @@ import {
 } from "@/components/Nutrition/api/nutritionalPlan";
 import { NutritionalPlan } from "@/components/Nutrition/models/nutritionalPlan";
 import {
+    RESPONSE_MEAL_UUID,
+    RESPONSE_PLAN_UUID,
     responseEmptyPlanList,
     responseNutritionalPlanDetail,
     responseSinglePlanList,
@@ -37,13 +39,17 @@ describe("Nutritional plan service tests", () => {
 
     test('GET plans - sparse', async () => {
 
+        const PLAN_UUID_A = 'aaaaaaaa-0000-0000-0000-000000072559';
+        const PLAN_UUID_B = 'aaaaaaaa-0000-0000-0000-000000060131';
+        const PLAN_UUID_C = 'aaaaaaaa-0000-0000-0000-000000024752';
+
         const planResponse = {
             count: 2,
             next: null,
             previous: null,
             results: [
                 {
-                    "id": 72559,
+                    "id": PLAN_UUID_A,
                     "creation_date": "2023-05-26",
                     "start": "2023-06-01",
                     "end": "2023-06-30",
@@ -51,7 +57,7 @@ describe("Nutritional plan service tests", () => {
                     "only_logging": true,
                 },
                 {
-                    "id": 60131,
+                    "id": PLAN_UUID_B,
                     "creation_date": "2022-06-01",
                     "start": "2022-06-01",
                     "end": null,
@@ -59,7 +65,7 @@ describe("Nutritional plan service tests", () => {
                     "only_logging": false,
                 },
                 {
-                    "id": 24752,
+                    "id": PLAN_UUID_C,
                     "creation_date": "2023-08-01",
                     "start": "2023-08-01",
                     "end": "2023-08-31",
@@ -76,7 +82,7 @@ describe("Nutritional plan service tests", () => {
 
         expect(result).toStrictEqual([
             new NutritionalPlan({
-                id: 72559,
+                id: PLAN_UUID_A,
                 creationDate: new Date('2023-05-26'),
                 start: new Date('2023-06-01'),
                 end: new Date('2023-06-30'),
@@ -84,13 +90,13 @@ describe("Nutritional plan service tests", () => {
                 onlyLogging: true
             }),
             new NutritionalPlan({
-                id: 60131,
+                id: PLAN_UUID_B,
                 creationDate: new Date('2022-06-01'),
                 description: '',
                 onlyLogging: false
             }),
             new NutritionalPlan({
-                id: 24752,
+                id: PLAN_UUID_C,
                 creationDate: new Date('2023-08-01'),
                 start: new Date('2023-08-01'),
                 end: new Date('2023-08-31'),
@@ -125,11 +131,11 @@ describe("Nutritional plan service tests", () => {
         const result = await getLastNutritionalPlan();
 
         expect(result).toBeInstanceOf(NutritionalPlan);
-        expect(result!.id).toBe(101);
-        expect(getMealsForPlan).toHaveBeenCalledWith(101);
+        expect(result!.id).toBe(RESPONSE_PLAN_UUID);
+        expect(getMealsForPlan).toHaveBeenCalledWith(RESPONSE_PLAN_UUID);
         // Diary entries are filtered by plan id
         expect(getNutritionalDiaryEntries).toHaveBeenCalledWith({
-            filtersetQuery: { plan: 101 },
+            filtersetQuery: { plan: RESPONSE_PLAN_UUID },
         });
     });
 
@@ -142,24 +148,25 @@ describe("Nutritional plan service tests", () => {
     });
 
     test('getNutritionalPlanFull wires meals back to their diary entries by mealId', async () => {
-        // Two diary entries, one for meal 78 and one for an unrelated meal
+        const OTHER_MEAL_UUID = 'bbbbbbbb-0000-0000-0000-000000000099';
+        // Two diary entries, one for the matching meal and one for an unrelated meal
         const diaryEntries = [
-            { mealId: 78 },
-            { mealId: 99 },
-            { mealId: 78 },
+            { mealId: RESPONSE_MEAL_UUID },
+            { mealId: OTHER_MEAL_UUID },
+            { mealId: RESPONSE_MEAL_UUID },
         ];
-        const meals = [{ id: 78, diaryEntries: [] as { mealId: number }[] }];
+        const meals = [{ id: RESPONSE_MEAL_UUID, diaryEntries: [] as { mealId: string }[] }];
 
         (axios.get as Mock).mockResolvedValue({ data: responseNutritionalPlanDetail });
         (getMealsForPlan as Mock).mockResolvedValue(meals);
         (getNutritionalDiaryEntries as Mock).mockResolvedValue(diaryEntries);
 
-        const result = await getNutritionalPlanFull(101);
+        const result = await getNutritionalPlanFull(RESPONSE_PLAN_UUID);
 
         expect(result).not.toBeNull();
         // The meal collected only the entries that match its id
         expect(meals[0].diaryEntries).toHaveLength(2);
-        expect(meals[0].diaryEntries.every(e => e.mealId === 78)).toBe(true);
+        expect(meals[0].diaryEntries.every(e => e.mealId === RESPONSE_MEAL_UUID)).toBe(true);
         // Both data sources are wired into the plan
         expect(result!.diaryEntries).toBe(diaryEntries);
         expect(result!.meals).toBe(meals);
@@ -170,10 +177,10 @@ describe("Nutritional plan service tests", () => {
         (getMealsForPlan as Mock).mockResolvedValue([]);
         (getNutritionalDiaryEntries as Mock).mockResolvedValue([]);
 
-        await getNutritionalPlanFull(101, { filtersetQueryLogs: { datetime__date: "2024-08-01" } });
+        await getNutritionalPlanFull(RESPONSE_PLAN_UUID, { filtersetQueryLogs: { datetime__date: "2024-08-01" } });
 
         expect(getNutritionalDiaryEntries).toHaveBeenCalledWith({
-            filtersetQuery: { plan: 101, datetime__date: "2024-08-01" },
+            filtersetQuery: { plan: RESPONSE_PLAN_UUID, datetime__date: "2024-08-01" },
         });
     });
 
@@ -203,12 +210,12 @@ describe("Nutritional plan service tests", () => {
         });
         expect(body).not.toHaveProperty("id");
         expect(result).toBeInstanceOf(NutritionalPlan);
-        expect(result.id).toBe(101);
+        expect(result.id).toBe(RESPONSE_PLAN_UUID);
     });
 
     test('editNutritionalPlan PATCHes /nutritionplan/<id>/', async () => {
         const plan = new NutritionalPlan({
-            id: 101,
+            id: RESPONSE_PLAN_UUID,
             description: "edited",
             start: new Date("2024-06-01"),
             end: new Date("2024-08-31"),
@@ -221,18 +228,18 @@ describe("Nutritional plan service tests", () => {
 
         expect(axios.patch).toHaveBeenCalledTimes(1);
         const [url, body] = (axios.patch as Mock).mock.calls[0];
-        expect(url).toMatch(/\/api\/v2\/nutritionplan\/101\/$/);
-        expect(body).toMatchObject({ id: 101, description: "edited" });
+        expect(url).toMatch(new RegExp(`/api/v2/nutritionplan/${RESPONSE_PLAN_UUID}/$`));
+        expect(body).toMatchObject({ id: RESPONSE_PLAN_UUID, description: "edited" });
         expect(result.description).toBe("edited");
     });
 
     test('deleteNutritionalPlan DELETEs /nutritionplan/<id>/', async () => {
         (axios.delete as Mock).mockResolvedValue({ status: 204 });
 
-        await deleteNutritionalPlan(101);
+        await deleteNutritionalPlan(RESPONSE_PLAN_UUID);
 
         expect(axios.delete).toHaveBeenCalledWith(
-            expect.stringMatching(/\/api\/v2\/nutritionplan\/101\/$/),
+            expect.stringMatching(new RegExp(`/api/v2/nutritionplan/${RESPONSE_PLAN_UUID}/$`)),
             expect.anything()
         );
     });
diff --git a/src/components/Nutrition/api/nutritionalPlan.ts b/src/components/Nutrition/api/nutritionalPlan.ts
index b1456fd2a..3e2f47c20 100644
--- a/src/components/Nutrition/api/nutritionalPlan.ts
+++ b/src/components/Nutrition/api/nutritionalPlan.ts
@@ -33,7 +33,7 @@ export const getLastNutritionalPlan = async (): Promise<NutritionalPlan | null>
     return await getNutritionalPlanFull(receivedPlan.results[0].id);
 };
 
-export const getNutritionalPlanFull = async (id: number | null, options?: NutritionalPlanOptions): Promise<NutritionalPlan | null> => {
+export const getNutritionalPlanFull = async (id: string | null, options?: NutritionalPlanOptions): Promise<NutritionalPlan | null> => {
     if (id === null) {
         return null;
     }
@@ -81,7 +81,7 @@ export const editNutritionalPlan = async (plan: NutritionalPlan): Promise<Nutrit
     return nutritionalPlanAdapter.fromJson(response.data);
 };
 
-export const deleteNutritionalPlan = async (id: number): Promise<void> => {
+export const deleteNutritionalPlan = async (id: string): Promise<void> => {
     await axios.delete(
         makeUrl(API_NUTRITIONAL_PLAN_PATH, { id: id }),
         { headers: makeHeader() },
diff --git a/src/components/Nutrition/models/diaryEntry.ts b/src/components/Nutrition/models/diaryEntry.ts
index a2d7103c7..a78e1b9d3 100644
--- a/src/components/Nutrition/models/diaryEntry.ts
+++ b/src/components/Nutrition/models/diaryEntry.ts
@@ -6,9 +6,9 @@ import { Adapter } from "@/core/lib/Adapter";
 import { numberGramLocale } from "@/core/lib/numbers";
 
 export interface ApiNutritionDiaryType {
-    id: number,
-    plan: number,
-    meal: number | null,
+    id: string,
+    plan: string,
+    meal: string | null,
     ingredient: number,
     weight_unit: number,
     datetime: Date,
@@ -16,9 +16,9 @@ export interface ApiNutritionDiaryType {
 }
 
 export type DiaryEntryConstructorParams = {
-    id?: number;
-    planId: number;
-    mealId?: number | null;
+    id?: string;
+    planId: string;
+    mealId?: string | null;
     ingredientId: number;
     weightUnitId?: number | null;
     amount: number;
@@ -29,9 +29,9 @@ export type DiaryEntryConstructorParams = {
 
 export class DiaryEntry {
 
-    public id?: number | null;
-    public planId: number;
-    public mealId: number | null;
+    public id?: string | null;
+    public planId: string;
+    public mealId: string | null;
     public amount: number;
     public datetime: Date;
 
diff --git a/src/components/Nutrition/models/meal.ts b/src/components/Nutrition/models/meal.ts
index 7e5c06a4a..325401610 100644
--- a/src/components/Nutrition/models/meal.ts
+++ b/src/components/Nutrition/models/meal.ts
@@ -6,8 +6,8 @@ import { Adapter } from "@/core/lib/Adapter";
 import { dateTimeToHHMM, dateTimeToLocaleHHMM, HHMMToDateTime, isSameDay } from "@/core/lib/date";
 
 export interface ApiMealType {
-    id: number,
-    plan: number,
+    id: string,
+    plan: string,
     order: number,
     time: string | null,
     name: string
@@ -15,8 +15,8 @@ export interface ApiMealType {
 
 
 export type MealConstructorParams = {
-    id?: number | null;
-    planId?: number | null;
+    id?: string | null;
+    planId?: string | null;
     order?: number;
     time?: Date | null;
     name: string;
@@ -26,8 +26,8 @@ export type MealConstructorParams = {
 
 export class Meal {
 
-    public id: number | null = null;
-    public planId: number | null = null;
+    public id: string | null = null;
+    public planId: string | null = null;
     public order: number;
     public time: Date | null = null;
     public name: string;
diff --git a/src/components/Nutrition/models/mealItem.ts b/src/components/Nutrition/models/mealItem.ts
index d8504094b..b3e10a1d9 100644
--- a/src/components/Nutrition/models/mealItem.ts
+++ b/src/components/Nutrition/models/mealItem.ts
@@ -7,8 +7,8 @@ import { Adapter } from "@/core/lib/Adapter";
 import { numberGramLocale } from "@/core/lib/numbers";
 
 export interface ApiMealItemType {
-    id: number,
-    meal: number,
+    id: string,
+    meal: string,
     ingredient: number,
     weight_unit: number,
     order: number,
@@ -16,8 +16,8 @@ export interface ApiMealItemType {
 }
 
 export type MealItemConstructorParams = {
-    id?: number;
-    mealId: number;
+    id?: string;
+    mealId: string;
     amount: number;
     order: number;
 
@@ -29,8 +29,8 @@ export type MealItemConstructorParams = {
 };
 
 export class MealItem {
-    public id?: number | null;
-    public mealId: number;
+    public id?: string | null;
+    public mealId: string;
     public ingredientId: number;
     public weightUnitId: number | null;
     public amount: number;
@@ -91,7 +91,7 @@ export class MealItem {
         });
     }
 
-    diaryEntry(planId: number, date?: Date): DiaryEntry {
+    diaryEntry(planId: string, date?: Date): DiaryEntry {
         return new DiaryEntry({
             mealId: this.mealId,
             planId: planId,
diff --git a/src/components/Nutrition/models/nutritionalPlan.test.ts b/src/components/Nutrition/models/nutritionalPlan.test.ts
index 0ce5fe056..1e3dc6ccf 100644
--- a/src/components/Nutrition/models/nutritionalPlan.test.ts
+++ b/src/components/Nutrition/models/nutritionalPlan.test.ts
@@ -1,4 +1,4 @@
-import { NutritionalPlan } from "@/components/Nutrition/models/nutritionalPlan";
+import { NutritionalPlan, PSEUDO_MEAL_ID } from "@/components/Nutrition/models/nutritionalPlan";
 import { TEST_DIARY_ENTRY_3, TEST_DIARY_ENTRY_4 } from "@/tests/nutritionDiaryTestdata";
 import { TEST_MEAL_1, TEST_NUTRITIONAL_PLAN_1 } from "@/tests/nutritionTestdata";
 
@@ -139,7 +139,11 @@ describe("Test the nutritional plan model", () => {
     });
 
     test('7-day average returns zero values when no entries exist', () => {
-        const plan = new NutritionalPlan({ id: 1, creationDate: new Date(), description: 'test' });
+        const plan = new NutritionalPlan({
+            id: 'aaaaaaaa-0000-0000-0000-000000000001',
+            creationDate: new Date(),
+            description: 'test'
+        });
         const values = plan.loggedNutritionalValues7DayAvg;
 
         expect(values.energy).toBe(0);
@@ -151,7 +155,11 @@ describe("Test the nutritional plan model", () => {
     test('7-day average divides total by 7 without rounding', () => {
         // INGREDIENT_3: energy=60, protein=0.89, carbs=14, sugar=11.78, sodium=0.006 per 100g
         // ENTRY_3: 200g → energy=120; ENTRY_4: 20g → energy=12; total=132, avg=132/7≈18.857
-        const plan = new NutritionalPlan({ id: 1, creationDate: new Date(), description: 'test' });
+        const plan = new NutritionalPlan({
+            id: 'aaaaaaaa-0000-0000-0000-000000000001',
+            creationDate: new Date(),
+            description: 'test'
+        });
         plan.diaryEntries = [TEST_DIARY_ENTRY_3, TEST_DIARY_ENTRY_4];
 
         const values = plan.loggedNutritionalValues7DayAvg;
@@ -169,7 +177,7 @@ describe("Test the nutritional plan model", () => {
         const meal = TEST_NUTRITIONAL_PLAN_1.pseudoMealOthers('the name');
 
         // Assert
-        expect(meal.id).toBe(-1);
+        expect(meal.id).toBe(PSEUDO_MEAL_ID);
         expect(meal.name).toBe('the name');
         expect(meal.diaryEntries.length).toBe(2);
     });
@@ -178,7 +186,7 @@ describe("Test the nutritional plan model", () => {
 
         // Act
         const plan = new NutritionalPlan({
-            id: 1,
+            id: '00000000-0000-0000-0000-000000000001',
             creationDate: new Date(),
             description: 'test 1',
         });
diff --git a/src/components/Nutrition/models/nutritionalPlan.ts b/src/components/Nutrition/models/nutritionalPlan.ts
index e8d12d38b..263d686c6 100644
--- a/src/components/Nutrition/models/nutritionalPlan.ts
+++ b/src/components/Nutrition/models/nutritionalPlan.ts
@@ -12,11 +12,11 @@ export type GroupedDiaryEntries = {
     nutritionalValues: NutritionalValues;
 }
 
-export const PSEUDO_MEAL_ID = -1;
+export const PSEUDO_MEAL_ID = '00000000-0000-0000-0000-000000000000';
 
 
 type NutritionalPlanConstructorParams = {
-    id?: number | null,
+    id?: string | null,
     creationDate?: Date,
     start?: Date,
     end?: Date | null,
@@ -33,7 +33,7 @@ type NutritionalPlanConstructorParams = {
 
 
 export class NutritionalPlan {
-    id: number | null;
+    id: string | null;
     creationDate: Date;
     start: Date;
     end: Date | null;
diff --git a/src/components/Nutrition/queries/diary.ts b/src/components/Nutrition/queries/diary.ts
index f450cd69d..710fc24b7 100644
--- a/src/components/Nutrition/queries/diary.ts
+++ b/src/components/Nutrition/queries/diary.ts
@@ -14,7 +14,7 @@ export const useNutritionDiaryQuery = (options?: NutritionalDiaryEntriesOptions)
     queryKey: [QueryKey.NUTRITIONAL_PLAN_DIARY, JSON.stringify(options || {})],
 });
 
-export const useAddDiaryEntryQuery = (planId: number) => {
+export const useAddDiaryEntryQuery = (planId: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
@@ -25,7 +25,7 @@ export const useAddDiaryEntryQuery = (planId: number) => {
     });
 };
 
-export const useAddDiaryEntriesQuery = (planId: number) => {
+export const useAddDiaryEntriesQuery = (planId: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
@@ -36,18 +36,18 @@ export const useAddDiaryEntriesQuery = (planId: number) => {
     });
 };
 
-export const useDeleteDiaryEntryQuery = (planId: number) => {
+export const useDeleteDiaryEntryQuery = (planId: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
-        mutationFn: (id: number) => deleteNutritionalDiaryEntry(id),
+        mutationFn: (id: string) => deleteNutritionalDiaryEntry(id),
         onSuccess: () => queryClient.invalidateQueries({
             queryKey: [QueryKey.NUTRITIONAL_PLAN, planId]
         })
     });
 };
 
-export const useEditDiaryEntryQuery = (planId: number) => {
+export const useEditDiaryEntryQuery = (planId: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
diff --git a/src/components/Nutrition/queries/meal.ts b/src/components/Nutrition/queries/meal.ts
index 56f9194d9..9df20f48a 100644
--- a/src/components/Nutrition/queries/meal.ts
+++ b/src/components/Nutrition/queries/meal.ts
@@ -3,7 +3,7 @@ import { Meal } from "@/components/Nutrition/models/meal";
 import { addMeal, deleteMeal, editMeal } from "@/components/Nutrition/api/meal";
 import { QueryKey } from "@/core/lib/consts";
 
-export const useAddMealQuery = (planId: number) => {
+export const useAddMealQuery = (planId: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
@@ -15,11 +15,11 @@ export const useAddMealQuery = (planId: number) => {
         }
     });
 };
-export const useDeleteMealQuery = (planId: number) => {
+export const useDeleteMealQuery = (planId: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
-        mutationFn: (id: number) => deleteMeal(id),
+        mutationFn: (id: string) => deleteMeal(id),
         onSuccess: () => {
             queryClient.invalidateQueries({
                 queryKey: [QueryKey.NUTRITIONAL_PLAN, planId]
@@ -27,7 +27,7 @@ export const useDeleteMealQuery = (planId: number) => {
         }
     });
 };
-export const useEditMealQuery = (planId: number) => {
+export const useEditMealQuery = (planId: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
diff --git a/src/components/Nutrition/queries/mealItem.ts b/src/components/Nutrition/queries/mealItem.ts
index 380fcf5e8..007a12f70 100644
--- a/src/components/Nutrition/queries/mealItem.ts
+++ b/src/components/Nutrition/queries/mealItem.ts
@@ -3,7 +3,7 @@ import { MealItem } from "@/components/Nutrition/models/mealItem";
 import { addMealItem, deleteMealItem, editMealItem } from "@/components/Nutrition/api/mealItem";
 import { QueryKey } from "@/core/lib/consts";
 
-export const useAddMealItemQuery = (planId: number) => {
+export const useAddMealItemQuery = (planId: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
@@ -16,7 +16,7 @@ export const useAddMealItemQuery = (planId: number) => {
     });
 };
 
-export const useEditMealItemQuery = (planId: number) => {
+export const useEditMealItemQuery = (planId: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
@@ -29,11 +29,11 @@ export const useEditMealItemQuery = (planId: number) => {
     });
 };
 
-export const useDeleteMealItemQuery = (planId: number) => {
+export const useDeleteMealItemQuery = (planId: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
-        mutationFn: (id: number) => deleteMealItem(id),
+        mutationFn: (id: string) => deleteMealItem(id),
         onSuccess: () => {
             queryClient.invalidateQueries({
                 queryKey: [QueryKey.NUTRITIONAL_PLAN, planId]
diff --git a/src/components/Nutrition/queries/plan.ts b/src/components/Nutrition/queries/plan.ts
index 6a386f351..632dd9942 100644
--- a/src/components/Nutrition/queries/plan.ts
+++ b/src/components/Nutrition/queries/plan.ts
@@ -26,7 +26,7 @@ export function useFetchLastNutritionalPlanQuery() {
     });
 }
 
-export function useFetchNutritionalPlanQuery(planId: number) {
+export function useFetchNutritionalPlanQuery(planId: string) {
     return useQuery({
         queryKey: [QueryKey.NUTRITIONAL_PLAN, planId],
         queryFn: () => getNutritionalPlanFull(planId)
@@ -37,7 +37,7 @@ export function useFetchNutritionalPlanQuery(planId: number) {
  * Fetches the full nutritional plan (meals, etc.), but only the diary entries for
  * the given date
  */
-export function useFetchNutritionalPlanDateQuery(planId: number | null, dateStr: string, enabled = true) {
+export function useFetchNutritionalPlanDateQuery(planId: string | null, dateStr: string, enabled = true) {
     return useQuery({
         queryKey: [QueryKey.NUTRITIONAL_PLAN, planId, dateStr],
         queryFn: () => getNutritionalPlanFull(planId, { filtersetQueryLogs: { "datetime__eq": dateToYYYYMMDD(new Date(dateStr)) } }),
@@ -61,11 +61,11 @@ export const useAddNutritionalPlanQuery = () => {
     });
 };
 
-export const useDeleteNutritionalPlanQuery = (id: number) => {
+export const useDeleteNutritionalPlanQuery = (id: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
-        mutationFn: (id: number) => deleteNutritionalPlan(id),
+        mutationFn: (id: string) => deleteNutritionalPlan(id),
         onSuccess: () => {
             queryClient.invalidateQueries({
                 queryKey: [QueryKey.NUTRITIONAL_PLANS,]
@@ -76,7 +76,7 @@ export const useDeleteNutritionalPlanQuery = (id: number) => {
         }
     });
 };
-export const useEditNutritionalPlanQuery = (id: number) => {
+export const useEditNutritionalPlanQuery = (id: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
diff --git a/src/components/Nutrition/screens/NutritionDiaryOverview.tsx b/src/components/Nutrition/screens/NutritionDiaryOverview.tsx
index 6be974dc9..66e58e297 100644
--- a/src/components/Nutrition/screens/NutritionDiaryOverview.tsx
+++ b/src/components/Nutrition/screens/NutritionDiaryOverview.tsx
@@ -16,9 +16,9 @@ export const NutritionDiaryOverview = () => {
     const [t] = useTranslation();
     const params = useParams<{ planId: string, date: string }>();
 
-    const planId = parseInt(params.planId!);
-    if (Number.isNaN(planId)) {
-        return <p>Please pass an integer as the nutritional plan id.</p>;
+    const planId = params.planId ?? '';
+    if (planId === '') {
+        return <p>Please pass a UUID as the nutritional plan id.</p>;
     }
 
     const date = new Date(params.date!);
diff --git a/src/components/Nutrition/screens/PlanDetail.tsx b/src/components/Nutrition/screens/PlanDetail.tsx
index 32e36488a..ca298fbc0 100644
--- a/src/components/Nutrition/screens/PlanDetail.tsx
+++ b/src/components/Nutrition/screens/PlanDetail.tsx
@@ -21,9 +21,9 @@ import { useParams } from "react-router-dom";
 export const PlanDetail = () => {
     const [t] = useTranslation();
     const params = useParams<{ planId: string }>();
-    const planId = parseInt(params.planId ?? '');
-    if (Number.isNaN(planId)) {
-        return <p>Please pass an integer as the nutritional plan id.</p>;
+    const planId = params.planId ?? '';
+    if (planId === '') {
+        return <p>Please pass a UUID as the nutritional plan id.</p>;
     }
 
     // eslint-disable-next-line react-hooks/rules-of-hooks
diff --git a/src/components/Nutrition/widgets/DiaryOverview.tsx b/src/components/Nutrition/widgets/DiaryOverview.tsx
index c16a9b69e..eca650436 100644
--- a/src/components/Nutrition/widgets/DiaryOverview.tsx
+++ b/src/components/Nutrition/widgets/DiaryOverview.tsx
@@ -9,7 +9,7 @@ import { numberLocale } from "@/core/lib/numbers";
 import { makeLink, WgerLink } from "@/core/lib/url";
 
 export const DiaryOverview = (props: {
-    planId: number,
+    planId: string,
     logged: Map<string, GroupedDiaryEntries>,
     planned: NutritionalValues
 }) => {
diff --git a/src/components/Nutrition/widgets/MealDetail.tsx b/src/components/Nutrition/widgets/MealDetail.tsx
index 9a4c9c635..bd58a46ff 100644
--- a/src/components/Nutrition/widgets/MealDetail.tsx
+++ b/src/components/Nutrition/widgets/MealDetail.tsx
@@ -29,7 +29,7 @@ import { MealDetailDropdown } from "@/components/Nutrition/widgets/MealDetailDro
 import React, { useState } from "react";
 import { useTranslation } from "react-i18next";
 
-const MealItemListItem = (props: { mealItem: MealItem, planId: number, mealId: number }) => {
+const MealItemListItem = (props: { mealItem: MealItem, planId: string, mealId: string }) => {
     const [expandForm, setExpandForm] = useState(false);
     const handleToggleForm = () => setExpandForm(!expandForm);
 
@@ -63,7 +63,7 @@ const MealItemListItem = (props: { mealItem: MealItem, planId: number, mealId: n
     </>;
 };
 
-export const MealDetail = (props: { meal: Meal, planId: number, onlyLogging: boolean }) => {
+export const MealDetail = (props: { meal: Meal, planId: string, onlyLogging: boolean }) => {
     const theme = useTheme();
     const [t] = useTranslation();
     const [expandViewStats, setExpandViewStats] = useState(false);
diff --git a/src/components/Nutrition/widgets/MealDetailDropdown.tsx b/src/components/Nutrition/widgets/MealDetailDropdown.tsx
index 16cddf30a..d239ff0cb 100644
--- a/src/components/Nutrition/widgets/MealDetailDropdown.tsx
+++ b/src/components/Nutrition/widgets/MealDetailDropdown.tsx
@@ -17,7 +17,7 @@ import { SNACKBAR_AUTO_HIDE_DURATION } from "@/core/lib/consts";
 
 export const MealDetailDropdown = (props: {
     meal: Meal,
-    planId: number,
+    planId: string,
     onlyLogging: boolean,
     isExpanded: boolean,
     handleExpanded: () => void,
diff --git a/src/components/Nutrition/widgets/forms/MealForm.test.tsx b/src/components/Nutrition/widgets/forms/MealForm.test.tsx
index 26a2a1385..66c28a7e9 100644
--- a/src/components/Nutrition/widgets/forms/MealForm.test.tsx
+++ b/src/components/Nutrition/widgets/forms/MealForm.test.tsx
@@ -31,7 +31,7 @@ describe('Test the MealForm component', () => {
         // Act
         render(
             <QueryClientProvider client={queryClient}>
-                <MealForm planId={987} closeFn={closeFnMock} />
+                <MealForm planId="aaaaaaaa-0000-0000-0000-000000000987" closeFn={closeFnMock} />
             </QueryClientProvider>
         );
 
@@ -47,7 +47,7 @@ describe('Test the MealForm component', () => {
         expect(closeFnMock).toHaveBeenCalled();
         expect(mutateAddMock).toHaveBeenCalledWith(new Meal({
             name: '2nd breakfast',
-            planId: 987,
+            planId: 'aaaaaaaa-0000-0000-0000-000000000987',
             time: expect.any(Date),
         }));
     });
@@ -59,7 +59,7 @@ describe('Test the MealForm component', () => {
         // Act
         render(
             <QueryClientProvider client={queryClient}>
-                <MealForm planId={987} meal={TEST_MEAL_1} closeFn={closeFnMock} />
+                <MealForm planId="aaaaaaaa-0000-0000-0000-000000000987" meal={TEST_MEAL_1} closeFn={closeFnMock} />
             </QueryClientProvider>
         );
 
@@ -75,10 +75,10 @@ describe('Test the MealForm component', () => {
         expect(closeFnMock).toHaveBeenCalled();
         expect(mutateEditMock).toHaveBeenCalledWith(
             expect.objectContaining({
-                id: 78,
+                id: 'bbbbbbbb-0000-0000-0000-000000000078',
                 name: '2nd breakfast',
                 order: 2,
-                planId: 123,
+                planId: 'aaaaaaaa-0000-0000-0000-000000000123',
                 time: TEST_MEAL_1.time
             })
         );
diff --git a/src/components/Nutrition/widgets/forms/MealForm.tsx b/src/components/Nutrition/widgets/forms/MealForm.tsx
index 4a89bf308..f5f83ae1b 100644
--- a/src/components/Nutrition/widgets/forms/MealForm.tsx
+++ b/src/components/Nutrition/widgets/forms/MealForm.tsx
@@ -10,7 +10,7 @@ import { useTranslation } from "react-i18next";
 import * as yup from "yup";
 
 interface MealFormProps {
-    planId: number,
+    planId: string,
     meal?: Meal,
     closeFn?: () => void,
 }
diff --git a/src/components/Nutrition/widgets/forms/MealItemForm.test.tsx b/src/components/Nutrition/widgets/forms/MealItemForm.test.tsx
index 7e3a5de40..d2ecaea8b 100644
--- a/src/components/Nutrition/widgets/forms/MealItemForm.test.tsx
+++ b/src/components/Nutrition/widgets/forms/MealItemForm.test.tsx
@@ -66,7 +66,8 @@ describe('Test the MealItemForm component', () => {
         // Act
         render(
             <QueryClientProvider client={queryClient}>
-                <MealItemForm mealId={123} planId={987} closeFn={closeFnMock} />
+                <MealItemForm mealId="bbbbbbbb-0000-0000-0000-000000000123"
+                              planId="aaaaaaaa-0000-0000-0000-000000000987" closeFn={closeFnMock} />
             </QueryClientProvider>
         );
         await fillInEntry(user);
@@ -78,7 +79,7 @@ describe('Test the MealItemForm component', () => {
         expect(closeFnMock).toHaveBeenCalled();
         expect(mutateAddMock).toHaveBeenCalledWith(
             expect.objectContaining({
-                mealId: 123,
+                mealId: 'bbbbbbbb-0000-0000-0000-000000000123',
                 amount: 120,
                 ingredientId: 101,
                 weightUnitId: null,
@@ -92,7 +93,8 @@ describe('Test the MealItemForm component', () => {
         // Act
         render(
             <QueryClientProvider client={queryClient}>
-                <MealItemForm planId={987} item={TEST_MEAL_ITEM_1} closeFn={closeFnMock} />
+                <MealItemForm planId="aaaaaaaa-0000-0000-0000-000000000987" item={TEST_MEAL_ITEM_1}
+                              closeFn={closeFnMock} />
             </QueryClientProvider>
         );
         await fillInEntry(user);
@@ -104,8 +106,8 @@ describe('Test the MealItemForm component', () => {
         expect(closeFnMock).toHaveBeenCalled();
         expect(mutateEditMock).toHaveBeenCalledWith(
             expect.objectContaining({
-                id: 42,
-                mealId: 1001,
+                id: 'cccccccc-0000-0000-0000-000000000042',
+                mealId: 'bbbbbbbb-0000-0000-0000-000000001001',
                 amount: 120,
                 order: 3,
                 ingredientId: 101,
diff --git a/src/components/Nutrition/widgets/forms/MealItemForm.tsx b/src/components/Nutrition/widgets/forms/MealItemForm.tsx
index 3e55f0b8c..4a91f7854 100644
--- a/src/components/Nutrition/widgets/forms/MealItemForm.tsx
+++ b/src/components/Nutrition/widgets/forms/MealItemForm.tsx
@@ -16,8 +16,8 @@ import * as yup from "yup";
 const GRAM_UNIT_VALUE = 'g';
 
 type MealItemFormProps =
-    | { planId: number; item: MealItem; closeFn?: () => void; mealId?: number }
-    | { planId: number; mealId: number; item?: undefined; closeFn?: () => void };
+    | { planId: string; item: MealItem; closeFn?: () => void; mealId?: string }
+    | { planId: string; mealId: string; item?: undefined; closeFn?: () => void };
 
 export const MealItemForm = ({ planId, item, mealId, closeFn }: MealItemFormProps) => {
 
@@ -83,7 +83,7 @@ export const MealItemForm = ({ planId, item, mealId, closeFn }: MealItemFormProp
                 } else {
                     // Add
                     addMealItemQuery.mutate(new MealItem({
-                        mealId: mealId,
+                        mealId: mealId!,
                         amount: newAmount,
                         ingredientId: values.ingredient,
                         weightUnitId: selectedUnit?.id ?? null,
diff --git a/src/components/Nutrition/widgets/forms/NutritionDiaryEntryForm.test.tsx b/src/components/Nutrition/widgets/forms/NutritionDiaryEntryForm.test.tsx
index e83f81f1d..e73648f0f 100644
--- a/src/components/Nutrition/widgets/forms/NutritionDiaryEntryForm.test.tsx
+++ b/src/components/Nutrition/widgets/forms/NutritionDiaryEntryForm.test.tsx
@@ -63,7 +63,7 @@ describe('Test the NutritionDiaryEntryForm component', () => {
         // Act
         render(
             <QueryClientProvider client={queryClient}>
-                <NutritionDiaryEntryForm planId={123} closeFn={closeFnMock} />
+                <NutritionDiaryEntryForm planId="aaaaaaaa-0000-0000-0000-000000000123" closeFn={closeFnMock} />
             </QueryClientProvider>
         );
         await fillInEntry(user);
@@ -78,7 +78,7 @@ describe('Test the NutritionDiaryEntryForm component', () => {
                 amount: 120,
                 datetime: expect.any(Date),
                 ingredientId: 101,
-                planId: 123,
+                planId: 'aaaaaaaa-0000-0000-0000-000000000123',
                 mealId: null,
                 weightUnitId: null,
             })
@@ -91,7 +91,8 @@ describe('Test the NutritionDiaryEntryForm component', () => {
         // Act
         render(
             <QueryClientProvider client={queryClient}>
-                <NutritionDiaryEntryForm planId={123} mealId={456} closeFn={closeFnMock} />
+                <NutritionDiaryEntryForm planId="aaaaaaaa-0000-0000-0000-000000000123"
+                                         mealId="bbbbbbbb-0000-0000-0000-000000000456" closeFn={closeFnMock} />
             </QueryClientProvider>
         );
         await fillInEntry(user);
@@ -106,8 +107,8 @@ describe('Test the NutritionDiaryEntryForm component', () => {
                 amount: 120,
                 datetime: expect.any(Date),
                 ingredientId: 101,
-                planId: 123,
-                mealId: 456,
+                planId: 'aaaaaaaa-0000-0000-0000-000000000123',
+                mealId: 'bbbbbbbb-0000-0000-0000-000000000456',
                 weightUnitId: null,
 
             })
@@ -121,7 +122,8 @@ describe('Test the NutritionDiaryEntryForm component', () => {
         // Act
         render(
             <QueryClientProvider client={queryClient}>
-                <NutritionDiaryEntryForm planId={123} entry={TEST_DIARY_ENTRY_1} closeFn={closeFnMock} />
+                <NutritionDiaryEntryForm planId="aaaaaaaa-0000-0000-0000-000000000123" entry={TEST_DIARY_ENTRY_1}
+                                         closeFn={closeFnMock} />
             </QueryClientProvider>
         );
         await fillInEntry(user);
@@ -131,10 +133,10 @@ describe('Test the NutritionDiaryEntryForm component', () => {
         expect(closeFnMock).toHaveBeenCalled();
         expect(mutateEditMock).toHaveBeenCalledWith(
             expect.objectContaining({
-                id: 42,
+                id: 'dddddddd-0000-0000-0000-000000000042',
                 amount: 120,
-                mealId: 78,
-                planId: 123,
+                mealId: 'bbbbbbbb-0000-0000-0000-000000000078',
+                planId: 'aaaaaaaa-0000-0000-0000-000000000123',
                 ingredientId: 101,
             })
         );
@@ -147,7 +149,9 @@ describe('Test the NutritionDiaryEntryForm component', () => {
         // Act
         render(
             <QueryClientProvider client={queryClient}>
-                <NutritionDiaryEntryForm planId={123} mealId={456} entry={TEST_DIARY_ENTRY_1} closeFn={closeFnMock} />
+                <NutritionDiaryEntryForm planId="aaaaaaaa-0000-0000-0000-000000000123"
+                                         mealId="bbbbbbbb-0000-0000-0000-000000000456" entry={TEST_DIARY_ENTRY_1}
+                                         closeFn={closeFnMock} />
             </QueryClientProvider>
         );
         await fillInEntry(user);
@@ -157,9 +161,9 @@ describe('Test the NutritionDiaryEntryForm component', () => {
         expect(closeFnMock).toHaveBeenCalled();
         expect(mutateEditMock).toHaveBeenCalledWith(
             expect.objectContaining({
-                id: 42,
-                planId: 123,
-                mealId: 456,
+                id: 'dddddddd-0000-0000-0000-000000000042',
+                planId: 'aaaaaaaa-0000-0000-0000-000000000123',
+                mealId: 'bbbbbbbb-0000-0000-0000-000000000456',
                 amount: 120,
                 ingredientId: 101,
                 weightUnitId: null,
diff --git a/src/components/Nutrition/widgets/forms/NutritionDiaryEntryForm.tsx b/src/components/Nutrition/widgets/forms/NutritionDiaryEntryForm.tsx
index 9a26b8de1..cf81a03e5 100644
--- a/src/components/Nutrition/widgets/forms/NutritionDiaryEntryForm.tsx
+++ b/src/components/Nutrition/widgets/forms/NutritionDiaryEntryForm.tsx
@@ -17,9 +17,9 @@ import * as yup from "yup";
 const GRAM_UNIT_VALUE = 'g';
 
 type NutritionDiaryEntryFormProps = {
-    planId: number,
+    planId: string,
     entry?: DiaryEntry,
-    mealId?: number | null,
+    mealId?: string | null,
     meals?: Meal[],
     closeFn?: () => void,
 }
@@ -33,7 +33,7 @@ export const NutritionDiaryEntryForm = ({ planId, entry, mealId, meals, closeFn
     const addDiaryQuery = useAddDiaryEntryQuery(planId);
     const editDiaryQuery = useEditDiaryEntryQuery(planId);
     const [dateValue, setDateValue] = useState<DateTime | null>(entry ? DateTime.fromJSDate(entry.datetime) : DateTime.now());
-    const [selectedMeal, setSelectedMeal] = useState<number | null>(meal);
+    const [selectedMeal, setSelectedMeal] = useState<string | null>(meal);
 
     const [selectedUnit, setSelectedUnit] = useState<NutritionWeightUnit | null>(entry?.weightUnit ?? null);
     const [weightUnits, setWeightUnits] = useState<NutritionWeightUnit[]>(entry?.ingredient?.weightUnits ?? []);
diff --git a/src/components/Nutrition/widgets/forms/PlanForm.test.tsx b/src/components/Nutrition/widgets/forms/PlanForm.test.tsx
index 7e720c7b2..4d98847b1 100644
--- a/src/components/Nutrition/widgets/forms/PlanForm.test.tsx
+++ b/src/components/Nutrition/widgets/forms/PlanForm.test.tsx
@@ -59,7 +59,7 @@ describe("Test the PlanForm component", () => {
         // Assert
         await user.click(screen.getByRole('button', { name: 'submit' }));
         expect(mutate).toHaveBeenCalledWith(expect.objectContaining({
-                id: 101,
+                id: 'aaaaaaaa-0000-0000-0000-000000000101',
                 description: "a better name",
                 // the existing plan's dates must be preserved when only the description changes
                 start: TEST_NUTRITIONAL_PLAN_1.start,
diff --git a/src/components/Nutrition/widgets/forms/PlanForm.tsx b/src/components/Nutrition/widgets/forms/PlanForm.tsx
index 588ad6b00..9a570ab0c 100644
--- a/src/components/Nutrition/widgets/forms/PlanForm.tsx
+++ b/src/components/Nutrition/widgets/forms/PlanForm.tsx
@@ -32,7 +32,7 @@ export const PlanForm = ({ plan, closeFn }: PlanFormProps) => {
 
     const [t] = useTranslation();
     const addPlanQuery = useAddNutritionalPlanQuery();
-    const editPlanQuery = useEditNutritionalPlanQuery(plan?.id || 0);
+    const editPlanQuery = useEditNutritionalPlanQuery(plan?.id ?? '');
     const [useGoals, setUseGoals] = useState(plan?.hasAnyGoals);
     const [startDateValue, setStartDateValue] = useState<DateTime | null>(plan ? DateTime.fromJSDate(plan.start) : DateTime.now);
     const [endDateValue, setEndDateValue] = useState<DateTime | null>(plan && plan?.end !== null ? DateTime.fromJSDate(plan!.end) : null);
diff --git a/src/components/Routines/api/routine.test.ts b/src/components/Routines/api/routine.test.ts
index 6483b3149..521c1e0ef 100644
--- a/src/components/Routines/api/routine.test.ts
+++ b/src/components/Routines/api/routine.test.ts
@@ -115,7 +115,7 @@ describe("workout routine service tests", () => {
         expect(axios.get).toHaveBeenCalledTimes(1);
         expect(result).toStrictEqual([
             new WorkoutLog({
-                id: 2,
+                id: 'aaaaaaaa-aaaa-aaaa-aaaa-000000000002',
                 routineId: 1,
                 date: new Date("2023-05-10"),
                 iteration: 1,
@@ -132,7 +132,7 @@ describe("workout routine service tests", () => {
             }),
 
             new WorkoutLog({
-                id: 1,
+                id: 'aaaaaaaa-aaaa-aaaa-aaaa-000000000001',
                 routineId: 1,
                 date: new Date("2023-05-13"),
                 iteration: 1,
diff --git a/src/components/Routines/api/session.test.ts b/src/components/Routines/api/session.test.ts
index f4d43d0a5..5f7ea4ceb 100644
--- a/src/components/Routines/api/session.test.ts
+++ b/src/components/Routines/api/session.test.ts
@@ -1,13 +1,19 @@
-import axios from "axios";
+import * as exerciseService from "@/components/Exercises/api/exercise";
 import { addSession, editSession, getSessions, searchSession } from "@/components/Routines/api/session";
 import { WorkoutSession } from "@/components/Routines/models/WorkoutSession";
-import * as exerciseService from "@/components/Exercises/api/exercise";
 import { testExerciseBenchPress, testExerciseSquats } from "@/tests/exerciseTestdata";
+import axios from "axios";
 import type { Mock } from 'vitest';
 
 vi.mock("axios");
 vi.mock("@/components/Exercises/api/exercise");
 
+// Recognisable test-marker UUIDs matching the Django fixtures convention
+const SESSION_UUID = 'bbbbbbbb-bbbb-bbbb-bbbb-000000024284';
+const SESSION_UUID_2 = 'bbbbbbbb-bbbb-bbbb-bbbb-000000000001';
+const LOG_UUID_1 = 'aaaaaaaa-aaaa-aaaa-aaaa-000004072327';
+const LOG_UUID_2 = 'aaaaaaaa-aaaa-aaaa-aaaa-000004072329';
+
 describe("Session service tests", () => {
     beforeEach(() => {
         vi.resetAllMocks();
@@ -23,9 +29,9 @@ describe("Session service tests", () => {
                     previous: null,
                     results: [
                         {
-                            "id": 4072327,
+                            "id": LOG_UUID_1,
                             "date": "2025-08-07T00:00:00+02:00",
-                            "session": 24284,
+                            "session": SESSION_UUID,
                             "routine": 39764,
                             "iteration": 1,
                             "slot_entry": 316691,
@@ -43,9 +49,9 @@ describe("Session service tests", () => {
                             "rest_target": null
                         },
                         {
-                            "id": 4072329,
+                            "id": LOG_UUID_2,
                             "date": "2025-08-07T00:00:00+02:00",
-                            "session": 24284,
+                            "session": SESSION_UUID,
                             "routine": 39764,
                             "iteration": 1,
                             "slot_entry": 316693,
@@ -75,7 +81,7 @@ describe("Session service tests", () => {
                     previous: null,
                     results: [
                         {
-                            "id": 24284,
+                            "id": SESSION_UUID,
                             "routine": 39764,
                             "day": null,
                             "date": "2025-08-07",
@@ -96,7 +102,7 @@ describe("Session service tests", () => {
 
         // Assert
         expect(sessions).toHaveLength(1);
-        expect(sessions[0].id).toBe(24284);
+        expect(sessions[0].id).toBe(SESSION_UUID);
         expect(sessions[0].logs).toHaveLength(2);
         expect(sessions[0].logs[0].exerciseId).toBe(345);
         expect(sessions[0].logs[0].exerciseObj).toBeDefined();
@@ -155,11 +161,11 @@ describe("Session service tests", () => {
             count: 1, next: null, previous: null,
             results: [
                 {
-                    id: 24284, routine: 39764, day: 5,
+                    id: SESSION_UUID, routine: 39764, day: 5,
                     date: "2025-08-07",
                     notes: "ok",
                     impression: "3",
-                    time_start: "20:10:58", time_end: "23:28:21",  
+                    time_start: "20:10:58", time_end: "23:28:21",
                 },
             ],
         };
@@ -172,7 +178,7 @@ describe("Session service tests", () => {
         expect(url).toContain("routine=39764");
         expect(url).toContain("date=2025-08-07");
         expect(result).toBeInstanceOf(WorkoutSession);
-        expect(result?.id).toBe(24284);
+        expect(result?.id).toBe(SESSION_UUID);
     });
 
     test('searchSession returns null when count !== 1', async () => {
@@ -198,9 +204,9 @@ describe("Session service tests", () => {
     test('addSession POSTs the params and returns the parsed session', async () => {
         (axios.post as Mock).mockResolvedValue({
             data: {
-                id: 1, routine: 39764, day: 5, date: "2025-08-07",
+                id: SESSION_UUID_2, routine: 39764, day: 5, date: "2025-08-07",
                 notes: null, impression: "3",
-                time_start: null, time_end: null,  
+                time_start: null, time_end: null,
             },
         });
 
@@ -221,27 +227,27 @@ describe("Session service tests", () => {
             impression: "3",
         });
         expect(result).toBeInstanceOf(WorkoutSession);
-        expect(result.id).toBe(1);
+        expect(result.id).toBe(SESSION_UUID_2);
     });
 
     test('editSession PATCHes /workoutsession/<id>/ with the params', async () => {
         (axios.patch as Mock).mockResolvedValue({
             data: {
-                id: 24284, routine: 39764, day: 5, date: "2025-08-07",
+                id: SESSION_UUID, routine: 39764, day: 5, date: "2025-08-07",
                 notes: "edited", impression: "3",
-                time_start: null, time_end: null,  
+                time_start: null, time_end: null,
             },
         });
 
         const result = await editSession({
-            id: 24284,
+            id: SESSION_UUID,
             notes: "edited",
         });
 
         expect(axios.patch).toHaveBeenCalledTimes(1);
         const [url, body] = (axios.patch as Mock).mock.calls[0];
-        expect(url).toMatch(/\/api\/v2\/workoutsession\/24284\/$/);
-        expect(body).toEqual({ id: 24284, notes: "edited" });
+        expect(url).toMatch(new RegExp(`/api/v2/workoutsession/${SESSION_UUID}/$`));
+        expect(body).toEqual({ id: SESSION_UUID, notes: "edited" });
         expect(result.notes).toBe("edited");
     });
 });
\ No newline at end of file
diff --git a/src/components/Routines/api/workoutLogs.test.ts b/src/components/Routines/api/workoutLogs.test.ts
index 06cdd80df..696da8128 100644
--- a/src/components/Routines/api/workoutLogs.test.ts
+++ b/src/components/Routines/api/workoutLogs.test.ts
@@ -38,7 +38,7 @@ describe("workout logs service tests", () => {
         expect(axios.get).toHaveBeenCalledTimes(1);
         expect(result).toStrictEqual([
             new WorkoutLog({
-                id: 2,
+                id: 'aaaaaaaa-aaaa-aaaa-aaaa-000000000002',
                 routineId: 1,
                 date: new Date("2023-05-10"),
                 iteration: 1,
@@ -60,7 +60,7 @@ describe("workout logs service tests", () => {
             }),
 
             new WorkoutLog({
-                id: 1,
+                id: 'aaaaaaaa-aaaa-aaaa-aaaa-000000000001',
                 routineId: 1,
                 date: new Date("2023-05-13"),
                 iteration: 1,
@@ -100,7 +100,7 @@ describe("workout logs service tests", () => {
         expect(axios.get).toHaveBeenCalledTimes(1);
         expect(result).toStrictEqual([
             new WorkoutLog({
-                id: 2,
+                id: 'aaaaaaaa-aaaa-aaaa-aaaa-000000000002',
                 routineId: 1,
                 date: new Date("2023-05-10"),
                 iteration: 1,
@@ -124,7 +124,7 @@ describe("workout logs service tests", () => {
             }),
 
             new WorkoutLog({
-                id: 1,
+                id: 'aaaaaaaa-aaaa-aaaa-aaaa-000000000001',
                 routineId: 1,
                 date: new Date("2023-05-13"),
                 iteration: 1,
@@ -163,21 +163,23 @@ describe("workout logs service tests", () => {
     });
 
     test('deleteLog DELETEs /workoutlog/<id>/ and returns the response status', async () => {
+        const LOG_UUID = 'aaaaaaaa-aaaa-aaaa-aaaa-000000000007';
         (axios.delete as Mock).mockResolvedValue({ status: 204 });
 
-        const result = await deleteLog(7);
+        const result = await deleteLog(LOG_UUID);
 
         expect(axios.delete).toHaveBeenCalledTimes(1);
         expect(axios.delete).toHaveBeenCalledWith(
-            expect.stringMatching(/\/api\/v2\/workoutlog\/7\/$/),
+            expect.stringMatching(new RegExp(`/api/v2/workoutlog/${LOG_UUID}/$`)),
             expect.anything()
         );
         expect(result).toBe(204);
     });
 
     test('editLog PATCHes /workoutlog/<id>/ with the snake_case body and returns the parsed log', async () => {
+        const LOG_UUID = 'aaaaaaaa-aaaa-aaaa-aaaa-000000000005';
         const apiResponse = {
-            id: 5,
+            id: LOG_UUID,
             iteration: 1,
             date: "2024-08-01T08:00:00.000Z",
             exercise: 100,
@@ -197,7 +199,7 @@ describe("workout logs service tests", () => {
         (axios.patch as Mock).mockResolvedValue({ data: apiResponse });
 
         const log = new WorkoutLog({
-            id: 5,
+            id: LOG_UUID,
             routineId: 1,
             slotEntryId: 2,
             exerciseId: 100,
@@ -217,9 +219,9 @@ describe("workout logs service tests", () => {
 
         expect(axios.patch).toHaveBeenCalledTimes(1);
         const [url, body] = (axios.patch as Mock).mock.calls[0];
-        expect(url).toMatch(/\/api\/v2\/workoutlog\/5\/$/);
+        expect(url).toMatch(new RegExp(`/api/v2/workoutlog/${LOG_UUID}/$`));
         expect(body).toMatchObject({
-            id: 5,
+            id: LOG_UUID,
             exercise: 100,
 
             slot_entry: 2,
@@ -228,13 +230,15 @@ describe("workout logs service tests", () => {
             repetitions_unit: 1,
         });
         expect(result).toBeInstanceOf(WorkoutLog);
-        expect(result.id).toBe(5);
+        expect(result.id).toBe(LOG_UUID);
     });
 
     test('addLogs POSTs each entry sequentially and collects the parsed responses', async () => {
+        const LOG_UUID_1 = 'aaaaaaaa-aaaa-aaaa-aaaa-000000000001';
+        const LOG_UUID_2 = 'aaaaaaaa-aaaa-aaaa-aaaa-000000000002';
         const responses = [
             {
-                id: 1,
+                id: LOG_UUID_1,
                 iteration: 1,
                 date: "2024-08-01T00:00:00Z",
                 exercise: 100,
@@ -252,7 +256,7 @@ describe("workout logs service tests", () => {
                 rest_target: null
             },
             {
-                id: 2,
+                id: LOG_UUID_2,
                 iteration: 1,
                 date: "2024-08-02T00:00:00Z",
                 exercise: 100,
@@ -284,7 +288,7 @@ describe("workout logs service tests", () => {
         expect(url).toMatch(/\/api\/v2\/workoutlog\/$/);
         expect(result).toHaveLength(2);
         expect(result[0]).toBeInstanceOf(WorkoutLog);
-        expect(result.map(l => l.id)).toEqual([1, 2]);
+        expect(result.map(l => l.id)).toEqual([LOG_UUID_1, LOG_UUID_2]);
     });
 
     test('addLogs returns [] when given an empty list (no requests fire)', async () => {
diff --git a/src/components/Routines/api/workoutLogs.ts b/src/components/Routines/api/workoutLogs.ts
index 303836188..e7dc042a5 100644
--- a/src/components/Routines/api/workoutLogs.ts
+++ b/src/components/Routines/api/workoutLogs.ts
@@ -7,7 +7,7 @@ import { fetchPaginated } from "@/core/lib/requests";
 import { makeHeader, makeUrl } from "@/core/lib/url";
 import axios from "axios";
 
-export const deleteLog = async (id: number): Promise<number> => {
+export const deleteLog = async (id: string): Promise<number> => {
     const response = await axios.delete<number>(makeUrl(ApiPath.WORKOUT_LOG, { id: id }), {
         headers: makeHeader(),
     });
diff --git a/src/components/Routines/models/WorkoutLog.ts b/src/components/Routines/models/WorkoutLog.ts
index 8a3987cf0..19a00beb6 100644
--- a/src/components/Routines/models/WorkoutLog.ts
+++ b/src/components/Routines/models/WorkoutLog.ts
@@ -20,12 +20,12 @@ export interface LogEntryForm {
 
 
 export class WorkoutLog {
-    public id: number;
+    public id: string;
     public date: Date;
     public iteration: number | null;
     public exerciseId: number;
     public slotEntryId: number | null;
-    public sessionId: number | null;
+    public sessionId: string | null;
     public routineId: number | null;
 
     public repetitionUnitObj: RepetitionUnit | null;
@@ -48,11 +48,11 @@ export class WorkoutLog {
     public exerciseObj?: Exercise;
 
     constructor(data: {
-        id: number;
+        id: string;
         date: Date | string;
         iteration: number | null;
         slotEntryId: number | null;
-        sessionId?: number | null;
+        sessionId?: string | null;
         routineId?: number | null;
 
         exercise?: Exercise;
diff --git a/src/components/Routines/models/WorkoutSession.ts b/src/components/Routines/models/WorkoutSession.ts
index 41a37e260..1a6d3de78 100644
--- a/src/components/Routines/models/WorkoutSession.ts
+++ b/src/components/Routines/models/WorkoutSession.ts
@@ -21,11 +21,11 @@ export interface AddSessionParams {
 }
 
 export interface EditSessionParams extends Partial<AddSessionParams> {
-    id: number,
+    id: string,
 }
 
 interface WorkoutSessionParams {
-    id: number;
+    id: string;
     dayId: number;
     routineId: number;
     date: Date;
@@ -39,7 +39,7 @@ interface WorkoutSessionParams {
 
 export class WorkoutSession {
 
-    id: number;
+    id: string;
     dayId: number;
     routineId: number;
     date: Date;
diff --git a/src/components/Routines/queries/logs.ts b/src/components/Routines/queries/logs.ts
index 350f2507b..4c820a06e 100644
--- a/src/components/Routines/queries/logs.ts
+++ b/src/components/Routines/queries/logs.ts
@@ -7,7 +7,7 @@ export function useDeleteRoutineLogQuery(routineId: number) {
     const queryClient = useQueryClient();
 
     return useMutation({
-        mutationFn: (logId: number) => deleteLog(logId),
+        mutationFn: (logId: string) => deleteLog(logId),
         onSuccess: () => {
             queryClient.invalidateQueries({ queryKey: [QueryKey.ROUTINE_LOG_DATA, routineId] });
             queryClient.invalidateQueries({ queryKey: [QueryKey.ROUTINE_STATS, routineId] });
diff --git a/src/components/Routines/queries/sessions.ts b/src/components/Routines/queries/sessions.ts
index 7b09649d3..c70d485c2 100644
--- a/src/components/Routines/queries/sessions.ts
+++ b/src/components/Routines/queries/sessions.ts
@@ -31,7 +31,7 @@ export const useSessionsQuery = (options?: SessionQueryOptions) => useQuery({
 });
 
 
-export const useEditSessionQuery = (id: number) => {
+export const useEditSessionQuery = (id: string) => {
     const queryClient = useQueryClient();
 
     return useMutation({
diff --git a/src/components/Routines/widgets/LogWidgets.test.tsx b/src/components/Routines/widgets/LogWidgets.test.tsx
index 8d824398e..21f9afa4f 100644
--- a/src/components/Routines/widgets/LogWidgets.test.tsx
+++ b/src/components/Routines/widgets/LogWidgets.test.tsx
@@ -55,7 +55,7 @@ describe('ExerciseLog', () => {
         );
 
         await user.click(screen.getAllByRole('menuitem', { name: /delete/i })[0]);
-        expect(mockDeleteMutate).toHaveBeenCalledWith(5);
+        expect(mockDeleteMutate).toHaveBeenCalledWith('aaaaaaaa-aaaa-aaaa-aaaa-000000000005');
         expect(mockEditMutate).not.toHaveBeenCalled();
 
     });
diff --git a/src/components/Routines/widgets/LogWidgets.tsx b/src/components/Routines/widgets/LogWidgets.tsx
index 4ef71d138..7c33104d7 100644
--- a/src/components/Routines/widgets/LogWidgets.tsx
+++ b/src/components/Routines/widgets/LogWidgets.tsx
@@ -74,7 +74,7 @@ export const ExerciseLog = (props: { exercise: Exercise, routineId: number, logE
     };
 
     const handleDeleteClick = (id: GridRowId) => () => {
-        deleteLogQuery.mutate(id as number);
+        deleteLogQuery.mutate(id.toString());
         setRows(rows.filter((row) => row.id !== id));
     };
 
diff --git a/src/components/Routines/widgets/forms/SessionForm.test.tsx b/src/components/Routines/widgets/forms/SessionForm.test.tsx
index b3f0db088..84d820934 100644
--- a/src/components/Routines/widgets/forms/SessionForm.test.tsx
+++ b/src/components/Routines/widgets/forms/SessionForm.test.tsx
@@ -33,7 +33,7 @@ describe('SessionForm', () => {
         // Arrange
         const user = userEvent.setup();
         const mockSession = new WorkoutSession({
-            id: 0,
+            id: 'bbbbbbbb-bbbb-bbbb-bbbb-000000000000',
             dayId: 0,
             routineId: 0,
             date: new Date(),
@@ -93,7 +93,7 @@ describe('SessionForm', () => {
         const timeEndFormatted = timeEnd.toLocaleString(DateTime.TIME_SIMPLE, { locale: 'en-us' });
 
         const mockSession = new WorkoutSession({
-            id: 1,
+            id: 'bbbbbbbb-bbbb-bbbb-bbbb-000000000001',
             dayId: dayId,
             routineId: routineId,
             date: date.toJSDate(),
diff --git a/src/components/Routines/widgets/forms/SessionForm.tsx b/src/components/Routines/widgets/forms/SessionForm.tsx
index 7e72744f5..158e1c1e4 100644
--- a/src/components/Routines/widgets/forms/SessionForm.tsx
+++ b/src/components/Routines/widgets/forms/SessionForm.tsx
@@ -43,7 +43,7 @@ export const SessionForm = ({ initialSession, dayId, routineId, selectedDate, se
     const [session, setSession] = React.useState<WorkoutSession | undefined>(initialSession);
 
     const addSessionQuery = useAddSessionQuery();
-    const editSessionQuery = useEditSessionQuery(session?.id || 0);
+    const editSessionQuery = useEditSessionQuery(session?.id || '');
     const findSessionQuery = useFindSessionQuery(
         routineId,
         {
diff --git a/src/core/lib/url.ts b/src/core/lib/url.ts
index ccb6ec742..0c6551a88 100644
--- a/src/core/lib/url.ts
+++ b/src/core/lib/url.ts
@@ -4,7 +4,7 @@ import i18n from "@/i18n";
 import slug from "slug";
 
 interface makeUrlInterface {
-    id?: number,
+    id?: number | string,
     server?: string,
     objectMethod?: string,
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -100,7 +100,7 @@ export enum WgerLink {
     TROPHIES,
 }
 
-type UrlParams = { id: number, id2?: number, slug?: string, date?: string };
+type UrlParams = { id: number | string, id2?: number | string, slug?: string, date?: string };
 
 
 /*
diff --git a/src/tests/measurementsTestData.ts b/src/tests/measurementsTestData.ts
index 425d2f4e6..40df955ef 100644
--- a/src/tests/measurementsTestData.ts
+++ b/src/tests/measurementsTestData.ts
@@ -1,31 +1,36 @@
 import { MeasurementCategory } from "@/components/Measurements/models/Category";
 import { MeasurementEntry } from "@/components/Measurements/models/Entry";
 
+// Recognisable test-marker UUIDs matching the Django fixtures convention
+const CATEGORY_1 = 'cccccccc-cccc-cccc-cccc-000000000001';
+const CATEGORY_2 = 'cccccccc-cccc-cccc-cccc-000000000002';
+const entry = (n: number) => `dddddddd-dddd-dddd-dddd-${n.toString().padStart(12, '0')}`;
+
 export const TEST_MEASUREMENT_ENTRIES_1 = [
-    new MeasurementEntry(1, 1, new Date(2023, 1, 1, 8, 0), 10, "test note"),
-    new MeasurementEntry(2, 1, new Date(2023, 1, 1, 18, 30), 12, "evening measurement"),
-    new MeasurementEntry(3, 1, new Date(2023, 1, 2, 7, 45), 20, ""),
-    new MeasurementEntry(4, 1, new Date(2023, 1, 3, 9, 15), 30, "important note"),
-    new MeasurementEntry(5, 1, new Date(2023, 1, 4, 12, 0), 40, "this day was good"),
-    new MeasurementEntry(6, 1, new Date(2023, 1, 5, 8, 0), 50, ""),
-    new MeasurementEntry(7, 1, new Date(2023, 1, 6, 8, 0), 60, ""),
-    new MeasurementEntry(8, 1, new Date(2023, 1, 7, 8, 0), 70, ""),
+    new MeasurementEntry(entry(1), CATEGORY_1, new Date(2023, 1, 1, 8, 0), 10, "test note"),
+    new MeasurementEntry(entry(2), CATEGORY_1, new Date(2023, 1, 1, 18, 30), 12, "evening measurement"),
+    new MeasurementEntry(entry(3), CATEGORY_1, new Date(2023, 1, 2, 7, 45), 20, ""),
+    new MeasurementEntry(entry(4), CATEGORY_1, new Date(2023, 1, 3, 9, 15), 30, "important note"),
+    new MeasurementEntry(entry(5), CATEGORY_1, new Date(2023, 1, 4, 12, 0), 40, "this day was good"),
+    new MeasurementEntry(entry(6), CATEGORY_1, new Date(2023, 1, 5, 8, 0), 50, ""),
+    new MeasurementEntry(entry(7), CATEGORY_1, new Date(2023, 1, 6, 8, 0), 60, ""),
+    new MeasurementEntry(entry(8), CATEGORY_1, new Date(2023, 1, 7, 8, 0), 70, ""),
 ];
 
 export const TEST_MEASUREMENT_ENTRIES_2 = [
-    new MeasurementEntry(1, 2, new Date(2023, 3, 1, 7, 0), 11, ""),
-    new MeasurementEntry(2, 2, new Date(2023, 3, 1, 19, 0), 13, ""),
-    new MeasurementEntry(3, 2, new Date(2023, 3, 2, 8, 30), 22, ""),
-    new MeasurementEntry(4, 2, new Date(2023, 3, 3, 9, 0), 33, ""),
-    new MeasurementEntry(5, 2, new Date(2023, 3, 4, 10, 15), 44, ""),
-    new MeasurementEntry(6, 2, new Date(2023, 3, 5, 7, 45), 55, ""),
-    new MeasurementEntry(7, 2, new Date(2023, 3, 6, 8, 0), 66, ""),
-    new MeasurementEntry(8, 2, new Date(2023, 3, 7, 8, 0), 77, ""),
+    new MeasurementEntry(entry(101), CATEGORY_2, new Date(2023, 3, 1, 7, 0), 11, ""),
+    new MeasurementEntry(entry(102), CATEGORY_2, new Date(2023, 3, 1, 19, 0), 13, ""),
+    new MeasurementEntry(entry(103), CATEGORY_2, new Date(2023, 3, 2, 8, 30), 22, ""),
+    new MeasurementEntry(entry(104), CATEGORY_2, new Date(2023, 3, 3, 9, 0), 33, ""),
+    new MeasurementEntry(entry(105), CATEGORY_2, new Date(2023, 3, 4, 10, 15), 44, ""),
+    new MeasurementEntry(entry(106), CATEGORY_2, new Date(2023, 3, 5, 7, 45), 55, ""),
+    new MeasurementEntry(entry(107), CATEGORY_2, new Date(2023, 3, 6, 8, 0), 66, ""),
+    new MeasurementEntry(entry(108), CATEGORY_2, new Date(2023, 3, 7, 8, 0), 77, ""),
 ];
 
 
 export const TEST_MEASUREMENT_CATEGORY_1 = new MeasurementCategory(
-    1,
+    CATEGORY_1,
     "Biceps",
     "cm",
     TEST_MEASUREMENT_ENTRIES_1,
@@ -33,8 +38,8 @@ export const TEST_MEASUREMENT_CATEGORY_1 = new MeasurementCategory(
 
 
 export const TEST_MEASUREMENT_CATEGORY_2 = new MeasurementCategory(
-    2,
+    CATEGORY_2,
     "Body fat",
     "%",
     TEST_MEASUREMENT_ENTRIES_2
-);
\ No newline at end of file
+);
diff --git a/src/tests/nutritionDiaryTestdata.ts b/src/tests/nutritionDiaryTestdata.ts
index dc916b70f..70674f0c7 100644
--- a/src/tests/nutritionDiaryTestdata.ts
+++ b/src/tests/nutritionDiaryTestdata.ts
@@ -3,9 +3,9 @@ import { TEST_INGREDIENT_1, TEST_INGREDIENT_2, TEST_INGREDIENT_3, TEST_INGREDIEN
 
 
 export const TEST_DIARY_ENTRY_1 = new DiaryEntry({
-    id: 42,
-    planId: 1,
-    mealId: 78,
+    id: 'dddddddd-0000-0000-0000-000000000042',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000078',
     ingredientId: 101,
     weightUnitId: null,
     amount: 120,
@@ -14,9 +14,9 @@ export const TEST_DIARY_ENTRY_1 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_2 = new DiaryEntry({
-    id: 44,
-    planId: 1,
-    mealId: 78,
+    id: 'dddddddd-0000-0000-0000-000000000044',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000078',
     ingredientId: 102,
     weightUnitId: null,
     amount: 50,
@@ -25,9 +25,9 @@ export const TEST_DIARY_ENTRY_2 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_3 = new DiaryEntry({
-    id: 45,
-    planId: 1,
-    mealId: 78,
+    id: 'dddddddd-0000-0000-0000-000000000045',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000078',
     ingredientId: 103,
     weightUnitId: null,
     amount: 200,
@@ -36,9 +36,9 @@ export const TEST_DIARY_ENTRY_3 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_4 = new DiaryEntry({
-    id: 46,
-    planId: 1,
-    mealId: 78,
+    id: 'dddddddd-0000-0000-0000-000000000046',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000078',
     ingredientId: 103,
     weightUnitId: null,
     amount: 20,
@@ -47,9 +47,9 @@ export const TEST_DIARY_ENTRY_4 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_5 = new DiaryEntry({
-    id: 47,
-    planId: 1,
-    mealId: 78,
+    id: 'dddddddd-0000-0000-0000-000000000047',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000078',
     ingredientId: 103,
     weightUnitId: null,
     amount: 20,
@@ -58,9 +58,9 @@ export const TEST_DIARY_ENTRY_5 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_6 = new DiaryEntry({
-    id: 48,
-    planId: 1,
-    mealId: 78,
+    id: 'dddddddd-0000-0000-0000-000000000048',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000078',
     ingredientId: 103,
     weightUnitId: null,
     amount: 50,
@@ -69,9 +69,9 @@ export const TEST_DIARY_ENTRY_6 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_7 = new DiaryEntry({
-    id: 49,
-    planId: 1,
-    mealId: 78,
+    id: 'dddddddd-0000-0000-0000-000000000049',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000078',
     ingredientId: 103,
     weightUnitId: null,
     amount: 50,
@@ -80,9 +80,9 @@ export const TEST_DIARY_ENTRY_7 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_8 = new DiaryEntry({
-    id: 50,
-    planId: 1,
-    mealId: 78,
+    id: 'dddddddd-0000-0000-0000-000000000050',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000078',
     ingredientId: 103,
     weightUnitId: null,
     amount: 100,
@@ -91,9 +91,9 @@ export const TEST_DIARY_ENTRY_8 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_9 = new DiaryEntry({
-    id: 51,
-    planId: 1,
-    mealId: 999,
+    id: 'dddddddd-0000-0000-0000-000000000051',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000999',
     ingredientId: 103,
     weightUnitId: null,
     amount: 80,
@@ -102,9 +102,9 @@ export const TEST_DIARY_ENTRY_9 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_10 = new DiaryEntry({
-    id: 51,
-    planId: 1,
-    mealId: 78,
+    id: 'dddddddd-0000-0000-0000-000000000051',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000078',
     ingredientId: 103,
     weightUnitId: null,
     amount: 80,
@@ -113,9 +113,9 @@ export const TEST_DIARY_ENTRY_10 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_11 = new DiaryEntry({
-    id: 52,
-    planId: 1,
-    mealId: 999,
+    id: 'dddddddd-0000-0000-0000-000000000052',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000999',
     ingredientId: 103,
     weightUnitId: null,
     amount: 500,
@@ -124,9 +124,9 @@ export const TEST_DIARY_ENTRY_11 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_12 = new DiaryEntry({
-    id: 52,
-    planId: 1,
-    mealId: 999,
+    id: 'dddddddd-0000-0000-0000-000000000052',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000999',
     ingredientId: 104,
     weightUnitId: null,
     amount: 500,
@@ -135,9 +135,9 @@ export const TEST_DIARY_ENTRY_12 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_13 = new DiaryEntry({
-    id: 53,
-    planId: 1,
-    mealId: 78,
+    id: 'dddddddd-0000-0000-0000-000000000053',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000078',
     ingredientId: 104,
     weightUnitId: null,
     amount: 500,
@@ -146,8 +146,8 @@ export const TEST_DIARY_ENTRY_13 = new DiaryEntry({
 });
 
 export const TEST_DIARY_ENTRY_14 = new DiaryEntry({
-    id: 54,
-    planId: 1,
+    id: 'dddddddd-0000-0000-0000-000000000054',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
     mealId: null,
     ingredientId: 104,
     weightUnitId: null,
@@ -156,8 +156,8 @@ export const TEST_DIARY_ENTRY_14 = new DiaryEntry({
     ingredient: TEST_INGREDIENT_4
 });
 export const TEST_DIARY_ENTRY_15 = new DiaryEntry({
-    id: 54,
-    planId: 1,
+    id: 'dddddddd-0000-0000-0000-000000000054',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000001',
     mealId: null,
     ingredientId: 103,
     weightUnitId: null,
diff --git a/src/tests/nutritionTestdata.ts b/src/tests/nutritionTestdata.ts
index 80b197027..c155b7aec 100644
--- a/src/tests/nutritionTestdata.ts
+++ b/src/tests/nutritionTestdata.ts
@@ -41,8 +41,8 @@ export const TEST_WEIGHT_UNIT_CUP = new NutritionWeightUnit(
 
 
 export const TEST_MEAL_ITEM_1 = new MealItem({
-    id: 42,
-    mealId: 1001,
+    id: 'cccccccc-0000-0000-0000-000000000042',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000001001',
     amount: 120,
     order: 3,
     ingredient: TEST_INGREDIENT_1,
@@ -50,8 +50,8 @@ export const TEST_MEAL_ITEM_1 = new MealItem({
     weightUnitId: null,
 });
 export const TEST_MEAL_ITEM_2 = new MealItem({
-    id: 43,
-    mealId: 1001,
+    id: 'cccccccc-0000-0000-0000-000000000043',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000001001',
     amount: 220,
     order: 1,
     ingredientId: 102,
@@ -59,8 +59,8 @@ export const TEST_MEAL_ITEM_2 = new MealItem({
     ingredient: TEST_INGREDIENT_2
 });
 export const TEST_MEAL_ITEM_3 = new MealItem({
-    id: 45,
-    mealId: 1001,
+    id: 'cccccccc-0000-0000-0000-000000000045',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000001001',
     amount: 320,
     order: 2,
     ingredientId: 104,
@@ -69,8 +69,8 @@ export const TEST_MEAL_ITEM_3 = new MealItem({
 });
 
 export const TEST_MEAL_ITEM_4 = new MealItem({
-    id: 46,
-    mealId: 999,
+    id: 'cccccccc-0000-0000-0000-000000000046',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000999',
     amount: 320,
     order: 1,
     ingredientId: 105,
@@ -79,8 +79,8 @@ export const TEST_MEAL_ITEM_4 = new MealItem({
 });
 
 export const TEST_MEAL_ITEM_5 = new MealItem({
-    id: 47,
-    mealId: 1,
+    id: 'cccccccc-0000-0000-0000-000000000047',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000001',
     amount: 320,
     order: 1,
     ingredientId: 101,
@@ -89,8 +89,8 @@ export const TEST_MEAL_ITEM_5 = new MealItem({
 });
 
 export const TEST_MEAL_ITEM_6 = new MealItem({
-    id: 48,
-    mealId: 123,
+    id: 'cccccccc-0000-0000-0000-000000000048',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000000123',
     amount: 100,
     order: 2,
     ingredientId: 102,
@@ -98,8 +98,8 @@ export const TEST_MEAL_ITEM_6 = new MealItem({
     ingredient: TEST_INGREDIENT_2
 });
 export const TEST_MEAL_ITEM_7 = new MealItem({
-    id: 103,
-    mealId: 2345,
+    id: 'cccccccc-0000-0000-0000-000000000103',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000002345',
     amount: 100,
     order: 1,
     ingredientId: 109,
@@ -108,8 +108,8 @@ export const TEST_MEAL_ITEM_7 = new MealItem({
 });
 
 export const TEST_MEAL_ITEM_8 = new MealItem({
-    id: 104,
-    mealId: 2222,
+    id: 'cccccccc-0000-0000-0000-000000000104',
+    mealId: 'bbbbbbbb-0000-0000-0000-000000002222',
     amount: 120,
     order: 1,
     ingredientId: 110,
@@ -119,8 +119,8 @@ export const TEST_MEAL_ITEM_8 = new MealItem({
 
 
 export const TEST_MEAL_1 = new Meal({
-    id: 78,
-    planId: 123,
+    id: 'bbbbbbbb-0000-0000-0000-000000000078',
+    planId: 'aaaaaaaa-0000-0000-0000-000000000123',
     order: 2,
     time: HHMMToDateTime('12:30'),
     name: 'Second breakfast',
@@ -129,7 +129,7 @@ TEST_MEAL_1.items = [TEST_MEAL_ITEM_1, TEST_MEAL_ITEM_2, TEST_MEAL_ITEM_3];
 
 
 export const TEST_MEAL_2 = new Meal({
-    id: 999,
+    id: 'bbbbbbbb-0000-0000-0000-000000000999',
     order: 3,
     time: HHMMToDateTime('22:30'),
     name: 'evening snack',
@@ -137,7 +137,7 @@ export const TEST_MEAL_2 = new Meal({
 TEST_MEAL_2.items = [TEST_MEAL_ITEM_4];
 
 export const TEST_MEAL_3 = new Meal({
-    id: 1,
+    id: 'bbbbbbbb-0000-0000-0000-000000000001',
     order: 1,
     time: HHMMToDateTime('6:30'),
     name: 'breakfast',
@@ -145,7 +145,7 @@ export const TEST_MEAL_3 = new Meal({
 TEST_MEAL_3.items = [TEST_MEAL_ITEM_5, TEST_MEAL_ITEM_6];
 
 export const TEST_MEAL_4 = new Meal({
-    id: 2,
+    id: 'bbbbbbbb-0000-0000-0000-000000000002',
     order: 1,
     time: HHMMToDateTime('7:45'),
     name: 'Cake time',
@@ -153,7 +153,7 @@ export const TEST_MEAL_4 = new Meal({
 TEST_MEAL_4.items = [TEST_MEAL_ITEM_7];
 
 export const TEST_MEAL_5 = new Meal({
-    id: 22,
+    id: 'bbbbbbbb-0000-0000-0000-000000000022',
     order: 2,
     time: HHMMToDateTime('12:00'),
     name: 'Time to visit McDonalds',
@@ -161,7 +161,7 @@ export const TEST_MEAL_5 = new Meal({
 TEST_MEAL_5.items = [TEST_MEAL_ITEM_8];
 
 export const TEST_NUTRITIONAL_PLAN_1 = new NutritionalPlan({
-    id: 101,
+    id: 'aaaaaaaa-0000-0000-0000-000000000101',
     creationDate: new Date('2023-01-01'),
     description: 'Summer body!!!',
 });
@@ -191,17 +191,25 @@ TEST_NUTRITIONAL_PLAN_1.diaryEntries = [
 
 
 export const TEST_NUTRITIONAL_PLAN_2 = new NutritionalPlan({
-    id: 222,
+    id: 'aaaaaaaa-0000-0000-0000-000000000222',
     creationDate: new Date('2023-08-01'),
     description: 'Bulking till we puke',
 });
 TEST_NUTRITIONAL_PLAN_2.meals = [TEST_MEAL_4, TEST_MEAL_5];
 
 
+// Recognisable test-marker UUIDs for the API response envelopes below
+export const RESPONSE_PLAN_UUID = 'aaaaaaaa-0000-0000-0000-000000000101';
+export const RESPONSE_PLAN_UUID_2 = 'aaaaaaaa-0000-0000-0000-000000000123';
+export const RESPONSE_MEAL_UUID = 'bbbbbbbb-0000-0000-0000-000000000078';
+export const RESPONSE_MEAL_ITEM_UUID = 'cccccccc-0000-0000-0000-000000000042';
+export const RESPONSE_MEAL_ITEM_UUID_2 = 'cccccccc-0000-0000-0000-000000000043';
+export const RESPONSE_DIARY_UUID = 'dddddddd-0000-0000-0000-000000000009';
+
 // API envelope for a single meal (POST/PATCH /meal/ response).
 export const responseMealDetail = {
-    id: 78,
-    plan: 123,
+    id: RESPONSE_MEAL_UUID,
+    plan: RESPONSE_PLAN_UUID_2,
     order: 2,
     time: '12:30',
     name: 'Second breakfast',
@@ -222,16 +230,16 @@ export const responseMealItemsForMeal = {
     previous: null,
     results: [
         {
-            id: 42,
-            meal: 78,
+            id: RESPONSE_MEAL_ITEM_UUID,
+            meal: RESPONSE_MEAL_UUID,
             ingredient: 101,
             weight_unit: null,
             order: 3,
             amount: '120.00',
         },
         {
-            id: 43,
-            meal: 78,
+            id: RESPONSE_MEAL_ITEM_UUID_2,
+            meal: RESPONSE_MEAL_UUID,
             ingredient: 102,
             weight_unit: null,
             order: 1,
@@ -242,8 +250,8 @@ export const responseMealItemsForMeal = {
 
 // Single mealitem envelope (POST/PATCH /mealitem/ response)
 export const responseMealItemDetail = {
-    id: 42,
-    meal: 78,
+    id: RESPONSE_MEAL_ITEM_UUID,
+    meal: RESPONSE_MEAL_UUID,
     ingredient: 101,
     weight_unit: null,
     order: 3,
@@ -252,7 +260,7 @@ export const responseMealItemDetail = {
 
 // Single nutritional plan envelope (POST/PATCH /nutritionplan/ response)
 export const responseNutritionalPlanDetail = {
-    id: 101,
+    id: RESPONSE_PLAN_UUID,
     creation_date: '2023-01-01',
     start: '2023-01-01',
     end: '2023-12-31',
@@ -288,9 +296,9 @@ export const responseDiaryEntries = {
     previous: null,
     results: [
         {
-            id: 9,
-            plan: 101,
-            meal: 78,
+            id: RESPONSE_DIARY_UUID,
+            plan: RESPONSE_PLAN_UUID,
+            meal: RESPONSE_MEAL_UUID,
             ingredient: 101,
             weight_unit: null,
             amount: '150.00',
@@ -301,9 +309,9 @@ export const responseDiaryEntries = {
 
 // Single diary entry envelope (POST/PATCH /nutritiondiary/ response)
 export const responseDiaryEntryDetail = {
-    id: 9,
-    plan: 101,
-    meal: 78,
+    id: RESPONSE_DIARY_UUID,
+    plan: RESPONSE_PLAN_UUID,
+    meal: RESPONSE_MEAL_UUID,
     ingredient: 101,
     weight_unit: null,
     amount: '150.00',
diff --git a/src/tests/workoutLogsRoutinesTestData.ts b/src/tests/workoutLogsRoutinesTestData.ts
index afc210422..94338bde5 100644
--- a/src/tests/workoutLogsRoutinesTestData.ts
+++ b/src/tests/workoutLogsRoutinesTestData.ts
@@ -4,7 +4,7 @@ import { testExerciseSquats } from "@/tests/exerciseTestdata";
 import { testRepUnitRepetitions, testWeightUnitKg } from "@/tests/workoutRoutinesTestData";
 
 const testWorkoutLog1 = new WorkoutLog({
-    id: 5,
+    id: 'aaaaaaaa-aaaa-aaaa-aaaa-000000000005',
     routineId: 1,
     date: new Date(2023, 1, 1),
     iteration: 345,
@@ -21,7 +21,7 @@ const testWorkoutLog1 = new WorkoutLog({
 });
 
 const testWorkoutLog2 = new WorkoutLog({
-    id: 6,
+    id: 'aaaaaaaa-aaaa-aaaa-aaaa-000000000006',
     routineId: 1,
     date: new Date(2023, 1, 2),
     iteration: 345,
@@ -38,7 +38,7 @@ const testWorkoutLog2 = new WorkoutLog({
 });
 
 const testWorkoutLog3 = new WorkoutLog({
-    id: 7,
+    id: 'aaaaaaaa-aaaa-aaaa-aaaa-000000000007',
     routineId: 1,
     date: new Date(2023, 1, 3),
     iteration: 345,
@@ -55,7 +55,7 @@ const testWorkoutLog3 = new WorkoutLog({
 });
 
 const testWorkoutLog4 = new WorkoutLog({
-    id: 8,
+    id: 'aaaaaaaa-aaaa-aaaa-aaaa-000000000008',
     routineId: 1,
     date: new Date(2023, 1, 10),
     iteration: 345,
@@ -79,7 +79,7 @@ export const testWorkoutLogs = [
 ];
 
 export const testWorkoutSession = new WorkoutSession({
-    id: 1,
+    id: 'bbbbbbbb-bbbb-bbbb-bbbb-000000000001',
     dayId: 2,
     routineId: 3,
     date: new Date(2025, 1, 10),
diff --git a/src/tests/workoutRoutinesTestData.ts b/src/tests/workoutRoutinesTestData.ts
index 562081ad1..f27abb6d1 100644
--- a/src/tests/workoutRoutinesTestData.ts
+++ b/src/tests/workoutRoutinesTestData.ts
@@ -205,7 +205,7 @@ export const testRoutineDayData1 = [
 export const testRoutineLogData = [
     new RoutineLogData(
         new WorkoutSession({
-            id: 111,
+            id: 'bbbbbbbb-bbbb-bbbb-bbbb-000000000111',
             dayId: 2,
             routineId: 1,
             date: new Date('2024-07-01'),
@@ -308,7 +308,7 @@ export const responseRoutineLogs = {
     "previous": null,
     "results": [
         {
-            "id": 2,
+            "id": "aaaaaaaa-aaaa-aaaa-aaaa-000000000002",
             "iteration": 1,
             "date": "2023-05-10",
             "exercise": 345,
@@ -327,7 +327,7 @@ export const responseRoutineLogs = {
             "rir_target": null
         },
         {
-            "id": 1,
+            "id": "aaaaaaaa-aaaa-aaaa-aaaa-000000000001",
             "iteration": 1,
             "date": "2023-05-13",
             "exercise": 345,
diff --git a/src/types.ts b/src/types.ts
index 1f57da219..a78dad30e 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -48,7 +48,7 @@ export interface ApiAliasType {
 }
 
 export interface ApiMeasurementCategoryType {
-    id: number,
+    id: string,
     name: string,
     unit: string
 }
@@ -112,7 +112,7 @@ export type ApiIngredientWeightUnitType = {
 }
 
 export interface ApiNutritionalPlanType {
-    id: number,
+    id: string,
     creation_date: string,
     start: string,
     end: string | null,
@@ -127,8 +127,8 @@ export interface ApiNutritionalPlanType {
 
 
 export interface ApiMeasurementEntryType {
-    id: number,
-    category: number,
+    id: string,
+    category: string,
     date: Date,
     value: number,
     notes: string