diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index d6cf375c..4c4ef2ea 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -154,6 +154,24 @@ An adapter is one JSON file; the rest is generated and checked.
 6. Drop the brand logo at
    `packages/frontend/public/logos/connectors/<icon>.svg`.
 
+### Translating the UI
+
+UI text lives in `packages/frontend/messages/<locale>.json` (English, German
+and Italian today), nested by area: `nav.*` for the sidebar, and so on.
+
+1. English is the source. Add a new key to `en.json` first and use it with
+   `useTranslations('<area>')` in client components or `getTranslations` in
+   server components.
+2. Add the same key to `de.json` and `it.json`. A key missing there falls back
+   to English, never to the raw key, but the key-parity test in
+   `tests/e2e/i18n.spec.ts` fails until every file has the same keys.
+3. Match the tone of the guides in `content/guides/de` and `content/guides/it`
+   (German uses *Sie*, Italian uses *tu*). If it isn't your native language,
+   say so in the PR so a maintainer can review those strings.
+
+The language comes from the `amcp_locale` cookie, then the browser's
+`Accept-Language`, then English (`src/i18n/request.ts`). URLs carry no locale.
+
 ### What Needs Discussion First
 
 Open an issue before starting work on:
diff --git a/package-lock.json b/package-lock.json
index cb39be74..d66be123 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -963,6 +963,31 @@
         "@electric-sql/pglite": "0.4.3"
       }
     },
+    "node_modules/@eloqnt/config": {
+      "version": "0.1.1",
+      "resolved": "https://registry.npmjs.org/@eloqnt/config/-/config-0.1.1.tgz",
+      "integrity": "sha512-YRDigSaiJEzKDfzTth5kG+L/PKfB3mo8h7yNzpXExPfvQmcD05WoZT57PdhJE0jI+Vva6eb0OCU8hnHHgdME3g==",
+      "license": "MIT"
+    },
+    "node_modules/@eloqnt/format-json": {
+      "version": "0.1.0",
+      "resolved": "https://registry.npmjs.org/@eloqnt/format-json/-/format-json-0.1.0.tgz",
+      "integrity": "sha512-4Pkb+HyzgWNJXoU48aJhUyNZSjZvMGooPCNG1ZFmBm55xTiNNPQCNXH66Ob6sXS6RvbWZrRpCf+Uo/Jz9K9g+A==",
+      "license": "MIT",
+      "dependencies": {
+        "@eloqnt/config": "^0.1.0"
+      }
+    },
+    "node_modules/@eloqnt/format-po": {
+      "version": "0.1.1",
+      "resolved": "https://registry.npmjs.org/@eloqnt/format-po/-/format-po-0.1.1.tgz",
+      "integrity": "sha512-aLtmIoqXGEaeTT0RcsLN8sZ3aIrsT/c/dVs28zrLhDjO3+vA3KNP+r98N0xq8w/k36+/GIUt4uZNbqcA71GVWw==",
+      "license": "MIT",
+      "dependencies": {
+        "@eloqnt/config": "^0.1.1",
+        "po-parser": "^2.2.0"
+      }
+    },
     "node_modules/@emnapi/runtime": {
       "version": "1.11.3",
       "resolved": "https://registry.npmjs.org/@emnapi/runtime/-/runtime-1.11.3.tgz",
@@ -1155,6 +1180,36 @@
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       "license": "MIT"
     },
+    "node_modules/@formatjs/fast-memoize": {
+      "version": "3.1.7",
+      "resolved": "https://registry.npmjs.org/@formatjs/fast-memoize/-/fast-memoize-3.1.7.tgz",
+      "integrity": "sha512-zXfhLpvA6T7+efdt9JLbBwZ00tT7NsBMDVnDu8rpHeNNv8KfRZAMo2gkG0k9lK/Nzc//3kJ9pImsfuJxk3KhUA==",
+      "license": "MIT"
+    },
+    "node_modules/@formatjs/icu-messageformat-parser": {
+      "version": "3.5.22",
+      "resolved": "https://registry.npmjs.org/@formatjs/icu-messageformat-parser/-/icu-messageformat-parser-3.5.22.tgz",
+      "integrity": "sha512-YuwN+dDKgssfuYwtOyGQD0CSn7K46g9cv1Fp0VgKpjZDDFvv8b8crzP990IcJhRPWHhKzCGsbUSJVIguyyFA5A==",
+      "license": "MIT",
+      "dependencies": {
+        "@formatjs/icu-skeleton-parser": "2.1.12"
+      }
+    },
+    "node_modules/@formatjs/icu-skeleton-parser": {
+      "version": "2.1.12",
+      "resolved": "https://registry.npmjs.org/@formatjs/icu-skeleton-parser/-/icu-skeleton-parser-2.1.12.tgz",
+      "integrity": "sha512-ca7tZMLpfHX3sUD7hP6gE/qr6Iq89EDd3ZLeRhbsB7r0UD55DGJq+tmFLzrGrnx5StahUevQmQQVtbDRHsfDHA==",
+      "license": "MIT"
+    },
+    "node_modules/@formatjs/intl-localematcher": {
+      "version": "0.8.14",
+      "resolved": "https://registry.npmjs.org/@formatjs/intl-localematcher/-/intl-localematcher-0.8.14.tgz",
+      "integrity": "sha512-8O7V38QmbB11+ryJ3KM/znrzXtiqgpXzqNoqDsndHZZ5/zDKTTL+cf5F0mzXkQEwhx8IlWnqYvEovf2S5EwLTw==",
+      "license": "MIT",
+      "dependencies": {
+        "@formatjs/fast-memoize": "3.1.7"
+      }
+    },
     "node_modules/@graphql-typed-document-node/core": {
       "version": "3.2.0",
       "resolved": "https://registry.npmjs.org/@graphql-typed-document-node/core/-/core-3.2.0.tgz",
@@ -5006,7 +5061,6 @@
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-      "dev": true,
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       "license": "MIT",
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@@ -5044,7 +5098,6 @@
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-      "dev": true,
       "license": "MIT",
       "optional": true,
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@@ -5065,7 +5118,6 @@
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-      "dev": true,
       "license": "MIT",
       "optional": true,
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@@ -5086,7 +5138,6 @@
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         "x64"
       ],
-      "dev": true,
       "license": "MIT",
       "optional": true,
       "os": [
@@ -5107,7 +5158,6 @@
       "cpu": [
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-      "dev": true,
       "license": "MIT",
       "optional": true,
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@@ -5128,7 +5178,6 @@
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-      "dev": true,
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@@ -5149,7 +5198,6 @@
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-      "dev": true,
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@@ -5170,7 +5218,6 @@
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@@ -5191,7 +5238,6 @@
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@@ -5212,7 +5258,6 @@
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@@ -5233,7 +5278,6 @@
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@@ -5254,7 +5298,6 @@
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-      "dev": true,
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       "optional": true,
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@@ -5275,7 +5318,6 @@
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-      "dev": true,
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@@ -5293,7 +5335,6 @@
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-      "dev": true,
       "license": "MIT"
     },
     "node_modules/@pinojs/redact": {
@@ -8383,6 +8424,12 @@
       "hasInstallScript": true,
       "license": "Apache-2.0"
     },
+    "node_modules/@schummar/icu-type-parser": {
+      "version": "1.21.5",
+      "resolved": "https://registry.npmjs.org/@schummar/icu-type-parser/-/icu-type-parser-1.21.5.tgz",
+      "integrity": "sha512-bXHSaW5jRTmke9Vd0h5P7BtWZG9Znqb8gSDxZnxaGSJnGwPLDPfS+3g0BKzeWqzgZPsIVZkM7m2tbo18cm5HBw==",
+      "license": "MIT"
+    },
     "node_modules/@sentry/browser": {
       "version": "10.76.2",
       "resolved": "https://registry.npmjs.org/@sentry/browser/-/browser-10.76.2.tgz",
@@ -9011,6 +9058,262 @@
       "devOptional": true,
       "license": "MIT"
     },
+    "node_modules/@swc/core": {
+      "version": "1.16.20",
+      "resolved": "https://registry.npmjs.org/@swc/core/-/core-1.16.20.tgz",
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+      "hasInstallScript": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "@swc/counter": "^0.1.3",
+        "@swc/types": "^0.1.28"
+      },
+      "engines": {
+        "node": ">=10"
+      },
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/swc"
+      },
+      "optionalDependencies": {
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+        "@swc/core-darwin-x64": "1.16.20",
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+        "@swc/core-linux-x64-musl": "1.16.20",
+        "@swc/core-win32-arm64-msvc": "1.16.20",
+        "@swc/core-win32-ia32-msvc": "1.16.20",
+        "@swc/core-win32-x64-msvc": "1.16.20"
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+      },
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+        }
+      }
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+      "os": [
+        "win32"
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+      }
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+      "version": "0.1.3",
+      "resolved": "https://registry.npmjs.org/@swc/counter/-/counter-0.1.3.tgz",
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+    },
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@@ -9020,6 +9323,15 @@
         "tslib": "^2.8.0"
       }
     },
+    "node_modules/@swc/types": {
+      "version": "0.1.28",
+      "resolved": "https://registry.npmjs.org/@swc/types/-/types-0.1.28.tgz",
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+      "license": "Apache-2.0",
+      "dependencies": {
+        "@swc/counter": "^0.1.3"
+      }
+    },
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@@ -15795,6 +16107,21 @@
         "url": "https://opencollective.com/express"
       }
     },
+    "node_modules/icu-minify": {
+      "version": "4.14.9",
+      "resolved": "https://registry.npmjs.org/icu-minify/-/icu-minify-4.14.9.tgz",
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+      "funding": [
+        {
+          "type": "individual",
+          "url": "https://github.com/sponsors/amannn"
+        }
+      ],
+      "license": "MIT",
+      "dependencies": {
+        "@formatjs/icu-messageformat-parser": "^3.4.0"
+      }
+    },
     "node_modules/ieee754": {
       "version": "1.2.1",
       "resolved": "https://registry.npmjs.org/ieee754/-/ieee754-1.2.1.tgz",
@@ -15930,6 +16257,31 @@
         "node": ">=12"
       }
     },
+    "node_modules/intl-messageformat": {
+      "version": "11.2.15",
+      "resolved": "https://registry.npmjs.org/intl-messageformat/-/intl-messageformat-11.2.15.tgz",
+      "integrity": "sha512-W4VNytsXyWgW5lvVchmsb9xgA5rSKqoflu3/IQ9UCtB0z4R+Bx9MoEkwFT/+30RCl/KzUoH0QGGe9lppF5SuvQ==",
+      "license": "BSD-3-Clause",
+      "dependencies": {
+        "@formatjs/fast-memoize": "3.1.7",
+        "@formatjs/icu-messageformat-parser": "3.5.18"
+      }
+    },
+    "node_modules/intl-messageformat/node_modules/@formatjs/icu-messageformat-parser": {
+      "version": "3.5.18",
+      "resolved": "https://registry.npmjs.org/@formatjs/icu-messageformat-parser/-/icu-messageformat-parser-3.5.18.tgz",
+      "integrity": "sha512-wX1efcL8d7K5QapOTRsP/OLTA/kpwe4LwqWyNxDNg5iRs8i9jJbCyxB5P8jc4KOW5oiLzz2DJr+BRY5xMV9+bA==",
+      "license": "MIT",
+      "dependencies": {
+        "@formatjs/icu-skeleton-parser": "2.1.11"
+      }
+    },
+    "node_modules/intl-messageformat/node_modules/@formatjs/icu-skeleton-parser": {
+      "version": "2.1.11",
+      "resolved": "https://registry.npmjs.org/@formatjs/icu-skeleton-parser/-/icu-skeleton-parser-2.1.11.tgz",
+      "integrity": "sha512-j8cUmOJzVgkHuS0QiQ6ga76UIoLOFSAMWhs7aZJztH3aAdCOAE6vpC8KVvFB4cU10ON0y2/5oOVmPJ43s2lTwA==",
+      "license": "MIT"
+    },
     "node_modules/ioredis": {
       "version": "5.11.1",
       "resolved": "https://registry.npmjs.org/ioredis/-/ioredis-5.11.1.tgz",
@@ -16179,7 +16531,6 @@
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/is-extglob/-/is-extglob-2.1.1.tgz",
       "integrity": "sha512-SbKbANkN603Vi4jEZv49LeVJMn4yGwsbzZworEoyEiutsN3nJYdbO36zfhGJ6QEDpOZIFkDtnq5JRxmvl3jsoQ==",
-      "dev": true,
       "license": "MIT",
       "engines": {
         "node": ">=0.10.0"
@@ -16244,7 +16595,6 @@
       "version": "4.0.3",
       "resolved": "https://registry.npmjs.org/is-glob/-/is-glob-4.0.3.tgz",
       "integrity": "sha512-xelSayHH36ZgE7ZWhli7pW34hNbNl8Ojv5KVmkJD4hBdD3th8Tfk9vYasLM+mXWOZhFkgZfxhLSnrwRr4elSSg==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "is-extglob": "^2.1.1"
@@ -19457,6 +19807,46 @@
         }
       }
     },
+    "node_modules/next-intl": {
+      "version": "4.14.9",
+      "resolved": "https://registry.npmjs.org/next-intl/-/next-intl-4.14.9.tgz",
+      "integrity": "sha512-uauRtUC+TrYNA1OL/QcwL9irndLrI9jK3Wdaa9W0B5AeKh9cqVdNeT0IWgLnhBqBRrVwppVdI0M+C1+JdGPQ3w==",
+      "funding": [
+        {
+          "type": "individual",
+          "url": "https://github.com/sponsors/amannn"
+        }
+      ],
+      "license": "MIT",
+      "dependencies": {
+        "@eloqnt/config": "^0.1.1",
+        "@eloqnt/format-json": "^0.1.0",
+        "@eloqnt/format-po": "^0.1.1",
+        "@formatjs/intl-localematcher": "^0.8.1",
+        "@parcel/watcher": "^2.4.1",
+        "@swc/core": "~1.16.0",
+        "icu-minify": "^4.14.9",
+        "negotiator": "^1.0.0",
+        "next-intl-swc-plugin-extractor": "4.14.9",
+        "use-intl": "^4.14.9"
+      },
+      "peerDependencies": {
+        "@types/react": "^16.8.0 || ^17.0.0 || ^18.0.0 || ^19.0.0",
+        "next": "^12.0.0 || ^13.0.0 || ^14.0.0 || ^15.0.0 || ^16.0.0",
+        "react": "^16.8.0 || ^17.0.0 || ^18.0.0 || >=19.0.0-rc <19.0.0 || ^19.0.0"
+      },
+      "peerDependenciesMeta": {
+        "@types/react": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/next-intl-swc-plugin-extractor": {
+      "version": "4.14.9",
+      "resolved": "https://registry.npmjs.org/next-intl-swc-plugin-extractor/-/next-intl-swc-plugin-extractor-4.14.9.tgz",
+      "integrity": "sha512-8jAkmDwQJo6RDavBHm9QRl1YTn2WXf+rI4SVhMaZxZcxopnwZic6fKTXOoNIo3kzC+a6vJySkOkXmHTVFLAYtg==",
+      "license": "MIT"
+    },
     "node_modules/next/node_modules/postcss": {
       "version": "8.5.23",
       "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.23.tgz",
@@ -20661,6 +21051,12 @@
         "node": ">=4"
       }
     },
+    "node_modules/po-parser": {
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/po-parser/-/po-parser-2.2.0.tgz",
+      "integrity": "sha512-NdTrKgh0oO7+y+RFX8KKhOB438x/j94UGXEFzl/7pHH0JjWSn42iJ9tgmPksIO6n1JKDHmNDcejPJfKspljB9g==",
+      "license": "MIT"
+    },
     "node_modules/possible-typed-array-names": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/possible-typed-array-names/-/possible-typed-array-names-1.1.0.tgz",
@@ -24234,6 +24630,33 @@
         }
       }
     },
+    "node_modules/use-intl": {
+      "version": "4.14.9",
+      "resolved": "https://registry.npmjs.org/use-intl/-/use-intl-4.14.9.tgz",
+      "integrity": "sha512-37ktvdCCz+6JY2VFPl/GV69Ds4ahiUT2c2xEZZRZYxdgGLxFsUbdxzjQVRm3YMIOUU0VPs6zvlifb4Yjk4IxIg==",
+      "funding": [
+        {
+          "type": "individual",
+          "url": "https://github.com/sponsors/amannn"
+        }
+      ],
+      "license": "MIT",
+      "dependencies": {
+        "@formatjs/fast-memoize": "^3.1.0",
+        "@schummar/icu-type-parser": "1.21.5",
+        "icu-minify": "^4.14.9",
+        "intl-messageformat": "^11.1.0"
+      },
+      "peerDependencies": {
+        "@types/react": "^17.0.0 || ^18.0.0 || ^19.0.0",
+        "react": "^17.0.0 || ^18.0.0 || >=19.0.0-rc <19.0.0 || ^19.0.0"
+      },
+      "peerDependenciesMeta": {
+        "@types/react": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/use-sidecar": {
       "version": "1.1.3",
       "resolved": "https://registry.npmjs.org/use-sidecar/-/use-sidecar-1.1.3.tgz",
@@ -25328,6 +25751,7 @@
         "clsx": "^2.1.1",
         "lucide-react": "^0.577.0",
         "next": "^16.4.2",
+        "next-intl": "^4.14.9",
         "react": "^19.3.1",
         "react-dom": "^19.3.1",
         "react-markdown": "^10.1.0",
diff --git a/packages/frontend/messages/de.json b/packages/frontend/messages/de.json
new file mode 100644
index 00000000..d5a364ae
--- /dev/null
+++ b/packages/frontend/messages/de.json
@@ -0,0 +1,31 @@
+{
+  "nav": {
+    "groups": {
+      "overview": "Übersicht",
+      "build": "Erstellen",
+      "intelligence": "Intelligenz",
+      "getStarted": "Erste Schritte"
+    },
+    "items": {
+      "dashboard": "Dashboard",
+      "analytics": "Analysen",
+      "auditLog": "Audit-Log",
+      "connectors": "Connectors",
+      "marketplace": "Marktplatz",
+      "mcpServers": "MCP-Server",
+      "knowledgeGraph": "Knowledge Graph",
+      "aiSkills": "KI-Skills",
+      "memory": "Gedächtnis",
+      "setup": "Einrichtung & Onboarding"
+    },
+    "settings": "Einstellungen",
+    "switchWorkspace": "Workspace wechseln",
+    "logOut": "Abmelden",
+    "workspaceFallback": "Workspace",
+    "githubStar": {
+      "label": "Stern auf GitHub",
+      "hide": "Schaltfläche ausblenden",
+      "hideAriaLabel": "Schaltfläche „Stern auf GitHub“ ausblenden"
+    }
+  }
+}
diff --git a/packages/frontend/messages/en.json b/packages/frontend/messages/en.json
new file mode 100644
index 00000000..c387a994
--- /dev/null
+++ b/packages/frontend/messages/en.json
@@ -0,0 +1,31 @@
+{
+  "nav": {
+    "groups": {
+      "overview": "Overview",
+      "build": "Build",
+      "intelligence": "Intelligence",
+      "getStarted": "Get started"
+    },
+    "items": {
+      "dashboard": "Dashboard",
+      "analytics": "Analytics",
+      "auditLog": "Audit Log",
+      "connectors": "Connectors",
+      "marketplace": "Marketplace",
+      "mcpServers": "MCP Servers",
+      "knowledgeGraph": "Knowledge Graph",
+      "aiSkills": "AI Skills",
+      "memory": "Memory",
+      "setup": "Setup & onboarding"
+    },
+    "settings": "Settings",
+    "switchWorkspace": "Switch workspace",
+    "logOut": "Log out",
+    "workspaceFallback": "Workspace",
+    "githubStar": {
+      "label": "Star on GitHub",
+      "hide": "Hide button",
+      "hideAriaLabel": "Hide Star on GitHub button"
+    }
+  }
+}
diff --git a/packages/frontend/messages/it.json b/packages/frontend/messages/it.json
new file mode 100644
index 00000000..f2329780
--- /dev/null
+++ b/packages/frontend/messages/it.json
@@ -0,0 +1,31 @@
+{
+  "nav": {
+    "groups": {
+      "overview": "Panoramica",
+      "build": "Crea",
+      "intelligence": "Intelligenza",
+      "getStarted": "Per iniziare"
+    },
+    "items": {
+      "dashboard": "Dashboard",
+      "analytics": "Analisi",
+      "auditLog": "Registro di audit",
+      "connectors": "Connettori",
+      "marketplace": "Marketplace",
+      "mcpServers": "Server MCP",
+      "knowledgeGraph": "Knowledge Graph",
+      "aiSkills": "Skill IA",
+      "memory": "Memoria",
+      "setup": "Setup e onboarding"
+    },
+    "settings": "Impostazioni",
+    "switchWorkspace": "Cambia workspace",
+    "logOut": "Esci",
+    "workspaceFallback": "Workspace",
+    "githubStar": {
+      "label": "Stella su GitHub",
+      "hide": "Nascondi pulsante",
+      "hideAriaLabel": "Nascondi il pulsante Stella su GitHub"
+    }
+  }
+}
diff --git a/packages/frontend/next.config.ts b/packages/frontend/next.config.ts
index 53980a5e..77c16a4b 100644
--- a/packages/frontend/next.config.ts
+++ b/packages/frontend/next.config.ts
@@ -1,5 +1,10 @@
 import type { NextConfig } from 'next';
 import { withSentryConfig } from '@sentry/nextjs/config';
+import createNextIntlPlugin from 'next-intl/plugin';
+
+// next-intl without i18n routing: no /de/... URL prefixes, so proxy.ts, the
+// rewrites below and every ?redirect= link keep working unchanged.
+const withNextIntl = createNextIntlPlugin('./src/i18n/request.ts');
 
 // Internal backend URL for rewrites — never use the public URL here to avoid loops
 const BACKEND_URL = process.env.BACKEND_INTERNAL_URL || 'http://localhost:4000';
@@ -42,7 +47,7 @@ const nextConfig: NextConfig = {
 // serves them. Self-hosted builds without the token skip the upload. Nothing
 // here decides where a running instance reports: that is SENTRY_DSN, read at
 // runtime (see components/sentry-config.tsx).
-export default withSentryConfig(nextConfig, {
+export default withSentryConfig(withNextIntl(nextConfig), {
   org: 'helpcodeai-gmbh',
   project: 'anythingmcp-cloud-frontend',
   // The organization is in Sentry's EU region.
diff --git a/packages/frontend/package.json b/packages/frontend/package.json
index 202b1637..6e1dd406 100644
--- a/packages/frontend/package.json
+++ b/packages/frontend/package.json
@@ -27,6 +27,7 @@
     "clsx": "^2.1.1",
     "lucide-react": "^0.577.0",
     "next": "^16.4.2",
+    "next-intl": "^4.14.9",
     "react": "^19.3.1",
     "react-dom": "^19.3.1",
     "react-markdown": "^10.1.0",
diff --git a/packages/frontend/src/app/layout.tsx b/packages/frontend/src/app/layout.tsx
index 2bf7e704..28cd0c34 100644
--- a/packages/frontend/src/app/layout.tsx
+++ b/packages/frontend/src/app/layout.tsx
@@ -44,6 +44,8 @@ import { GoogleTagManager, GoogleTagManagerNoscript } from '@/components/google-
 import { CookieConsentBanner } from '@/components/cookie-consent';
 import { SentryConfig } from '@/components/sentry-config';
 import { TRANSLATION_SAFE_DOM_SCRIPT } from '@/lib/translation-safe-dom';
+import { NextIntlClientProvider } from 'next-intl';
+import { getLocale } from 'next-intl/server';
 
 export const metadata: Metadata = {
   title: 'AnythingMCP — Custom connectors for Claude, ChatGPT, Copilot & any AI agent',
@@ -84,16 +86,18 @@ export const dynamic = 'force-dynamic';
 // Inline script to prevent FOUC — runs before React hydrates
 const themeScript = `(function(){try{var t=localStorage.getItem('theme');var d=t==='dark'||(t!=='light'&&matchMedia('(prefers-color-scheme:dark)').matches);if(d)document.documentElement.classList.add('dark')}catch(e){}})()`;
 
-export default function RootLayout({
+export default async function RootLayout({
   children,
 }: {
   children: React.ReactNode;
 }) {
   const gtmEnabled = Boolean(process.env.GTM_ID);
   const cookieDomain = process.env.COOKIE_DOMAIN;
+  // amcp_locale cookie, then Accept-Language, then English (src/i18n/request.ts).
+  const locale = await getLocale();
 
   return (
-    <html lang="en" className={`${Geist.variable} ${GeistMono.variable}`} suppressHydrationWarning>
+    <html lang={locale} className={`${Geist.variable} ${GeistMono.variable}`} suppressHydrationWarning>
       <head>
         <script dangerouslySetInnerHTML={{ __html: TRANSLATION_SAFE_DOM_SCRIPT }} />
         <script dangerouslySetInnerHTML={{ __html: themeScript }} />
@@ -102,10 +106,13 @@ export default function RootLayout({
       </head>
       <body>
         <GoogleTagManagerNoscript />
-        <Providers>
-          <LicenseWall />
-          {children}
-        </Providers>
+        {/* Almost every page is a client component, so the messages are passed once here. */}
+        <NextIntlClientProvider>
+          <Providers>
+            <LicenseWall />
+            {children}
+          </Providers>
+        </NextIntlClientProvider>
         {gtmEnabled && <CookieConsentBanner cookieDomain={cookieDomain} />}
       </body>
     </html>
diff --git a/packages/frontend/src/components/app-sidebar.tsx b/packages/frontend/src/components/app-sidebar.tsx
index 8bf3d846..97a9b050 100644
--- a/packages/frontend/src/components/app-sidebar.tsx
+++ b/packages/frontend/src/components/app-sidebar.tsx
@@ -3,6 +3,7 @@
 import Link from 'next/link';
 import { usePathname } from 'next/navigation';
 import { useState, useRef, useEffect } from 'react';
+import { useTranslations } from 'next-intl';
 import { useAuth } from '@/lib/auth-context';
 import { LogoIcon } from '@/components/logo-icon';
 import { cn } from '@/lib/utils';
@@ -72,6 +73,7 @@ function bestHref(pathname: string): string | null {
 
 export function AppSidebar({ mobileOpen, onClose }: { mobileOpen: boolean; onClose: () => void }) {
   const pathname = usePathname();
+  const t = useTranslations('nav');
   const { user, orgName, orgs, switchOrg, logout } = useAuth();
   const [wsMenu, setWsMenu] = useState(false);
   const wsRef = useRef<HTMLDivElement>(null);
@@ -108,7 +110,7 @@ export function AppSidebar({ mobileOpen, onClose }: { mobileOpen: boolean; onClo
         {NAV.map((g) => (
           <div key={g.group}>
             <div className="px-2.5 pb-1 pt-2.5 text-[10.5px] font-semibold uppercase tracking-[0.06em] text-[var(--text-3)]">
-              {g.group}
+              {t(`groups.${g.id}`)}
             </div>
             {g.items.map((item) => {
               const Icon = NAV_ICONS[item.href];
@@ -125,7 +127,7 @@ export function AppSidebar({ mobileOpen, onClose }: { mobileOpen: boolean; onClo
                   )}
                 >
                   {Icon && <Icon />}
-                  {item.label}
+                  {t(`items.${item.id}`)}
                 </Link>
               );
             })}
@@ -140,7 +142,7 @@ export function AppSidebar({ mobileOpen, onClose }: { mobileOpen: boolean; onClo
         {wsMenu && (
           <div className="absolute inset-x-3 bottom-[64px] z-50 overflow-hidden rounded-xl border border-[var(--border)] bg-[var(--surface)] shadow-[var(--shadow)]">
             <div className="px-3 py-2 text-[10.5px] font-semibold uppercase tracking-[0.05em] text-[var(--text-3)]">
-              Switch workspace
+              {t('switchWorkspace')}
             </div>
             {(Array.isArray(orgs) ? orgs : []).map((org) => {
               const isCurrent = org.id === user?.organizationId;
@@ -172,7 +174,7 @@ export function AppSidebar({ mobileOpen, onClose }: { mobileOpen: boolean; onClo
                 className="flex w-full items-center gap-2.5 px-3 py-2.5 text-left text-[13px] font-medium text-[var(--danger)] hover:bg-[var(--t-danger-bg)]"
               >
                 <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"><path d="M9 21H5a2 2 0 0 1-2-2V5a2 2 0 0 1 2-2h4M16 17l5-5-5-5M21 12H9" /></svg>
-                Log out
+                {t('logOut')}
               </button>
             </div>
           </div>
@@ -189,7 +191,7 @@ export function AppSidebar({ mobileOpen, onClose }: { mobileOpen: boolean; onClo
           )}
         >
           <SettingsIcon />
-          Settings
+          {t('settings')}
         </Link>
 
         <button
@@ -200,7 +202,7 @@ export function AppSidebar({ mobileOpen, onClose }: { mobileOpen: boolean; onClo
             {orgInitials}
           </div>
           <div className="min-w-0 flex-1">
-            <div className="truncate text-[12.5px] font-semibold text-[var(--text)]">{orgName || 'Workspace'}</div>
+            <div className="truncate text-[12.5px] font-semibold text-[var(--text)]">{orgName || t('workspaceFallback')}</div>
             <div className="text-[11px] text-[var(--text-3)]">{user?.email}</div>
           </div>
           <svg width="15" height="15" viewBox="0 0 24 24" fill="none" stroke="var(--text-3)" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"><path d="m7 15 5 5 5-5M7 9l5-5 5 5" /></svg>
diff --git a/packages/frontend/src/components/github-star-button.tsx b/packages/frontend/src/components/github-star-button.tsx
index 5c098cf8..6e566803 100644
--- a/packages/frontend/src/components/github-star-button.tsx
+++ b/packages/frontend/src/components/github-star-button.tsx
@@ -1,11 +1,13 @@
 'use client';
 
 import { useState, useEffect } from 'react';
+import { useTranslations } from 'next-intl';
 import { useEdition } from '@/lib/use-edition';
 
 const STORAGE_KEY = 'amcp:hide-github-star';
 
 export function GithubStarButton() {
+  const t = useTranslations('nav.githubStar');
   const { edition } = useEdition();
   const [dismissed, setDismissed] = useState(false);
   const [mounted, setMounted] = useState(false);
@@ -51,13 +53,13 @@ export function GithubStarButton() {
         >
           <path d="m12 3 2.2 4.6 5 .7-3.6 3.5.9 5L12 14.9 7.5 16.8l.9-5L4.8 8.3l5-.7z" />
         </svg>
-        <span className="truncate font-medium">Star on GitHub</span>
+        <span className="truncate font-medium">{t('label')}</span>
       </a>
       <button
         type="button"
         onClick={handleDismiss}
-        title="Hide button"
-        aria-label="Hide Star on GitHub button"
+        title={t('hide')}
+        aria-label={t('hideAriaLabel')}
         className="flex h-6 w-6 flex-shrink-0 items-center justify-center rounded-md text-[var(--text-3)] hover:bg-[var(--surface-2)] hover:text-[var(--text)] transition-colors"
       >
         <svg
diff --git a/packages/frontend/src/i18n/config.ts b/packages/frontend/src/i18n/config.ts
new file mode 100644
index 00000000..c7d4a606
--- /dev/null
+++ b/packages/frontend/src/i18n/config.ts
@@ -0,0 +1,44 @@
+// UI languages. English is the source: every key is defined in
+// messages/en.json, and the other files translate it.
+export const LOCALES = ['en', 'de', 'it'] as const;
+export type Locale = (typeof LOCALES)[number];
+export const DEFAULT_LOCALE: Locale = 'en';
+
+// A per-browser preference, not a workspace or instance setting, so members of
+// one workspace (and signed-out visitors on /login) can use different languages.
+export const LOCALE_COOKIE = 'amcp_locale';
+
+export function isLocale(value: string | undefined | null): value is Locale {
+  return !!value && (LOCALES as readonly string[]).includes(value);
+}
+
+/**
+ * The best supported language for an Accept-Language header, by quality.
+ * Only the primary subtag is compared (`de-AT` → `de`); `*` and unsupported
+ * languages are skipped, so `fr-FR` falls through to English.
+ */
+export function matchAcceptLanguage(header: string | null | undefined): Locale | null {
+  if (!header) return null;
+  const ranked = header
+    .split(',')
+    .map((part, index) => {
+      const [tag, ...params] = part.trim().split(';');
+      const q = params.map((p) => p.trim()).find((p) => p.startsWith('q='));
+      const quality = q ? Number(q.slice(2)) : 1;
+      return { tag: tag.trim().toLowerCase(), quality: Number.isNaN(quality) ? 0 : quality, index };
+    })
+    .filter((entry) => entry.tag && entry.tag !== '*' && entry.quality > 0)
+    .sort((a, b) => b.quality - a.quality || a.index - b.index);
+
+  for (const { tag } of ranked) {
+    const primary = tag.split('-')[0];
+    if (isLocale(primary)) return primary;
+  }
+  return null;
+}
+
+/** Cookie if it holds a supported locale, otherwise Accept-Language, otherwise English. */
+export function resolveLocale(cookieValue: string | undefined, acceptLanguage: string | null): Locale {
+  if (isLocale(cookieValue)) return cookieValue;
+  return matchAcceptLanguage(acceptLanguage) ?? DEFAULT_LOCALE;
+}
diff --git a/packages/frontend/src/i18n/request.ts b/packages/frontend/src/i18n/request.ts
new file mode 100644
index 00000000..5d77eecc
--- /dev/null
+++ b/packages/frontend/src/i18n/request.ts
@@ -0,0 +1,33 @@
+import { cookies, headers } from 'next/headers';
+import { getRequestConfig } from 'next-intl/server';
+import { DEFAULT_LOCALE, LOCALE_COOKIE, resolveLocale } from './config';
+import en from '../../messages/en.json';
+
+type Messages = { [key: string]: string | Messages };
+
+// A key missing from a translation falls back to the English text, never to
+// the raw key: the English file is the base and the locale's file is laid on top.
+function withEnglishFallback(base: Messages, translated: Messages): Messages {
+  const merged: Messages = { ...base };
+  for (const [key, value] of Object.entries(translated)) {
+    const baseValue = base[key];
+    merged[key] =
+      typeof value === 'object' && typeof baseValue === 'object'
+        ? withEnglishFallback(baseValue, value)
+        : value;
+  }
+  return merged;
+}
+
+export default getRequestConfig(async () => {
+  const cookieStore = await cookies();
+  const headerStore = await headers();
+  const locale = resolveLocale(cookieStore.get(LOCALE_COOKIE)?.value, headerStore.get('accept-language'));
+
+  const messages =
+    locale === DEFAULT_LOCALE
+      ? en
+      : withEnglishFallback(en, (await import(`../../messages/${locale}.json`)).default);
+
+  return { locale, messages };
+});
diff --git a/packages/frontend/src/lib/navigation.ts b/packages/frontend/src/lib/navigation.ts
index c5d48ff6..b0ebf7aa 100644
--- a/packages/frontend/src/lib/navigation.ts
+++ b/packages/frontend/src/lib/navigation.ts
@@ -1,10 +1,15 @@
 export interface NavItem {
+  /** Message key under `nav.items` (messages/*.json). */
+  id: string;
   href: string;
+  /** English label; the sidebar shows the translated `nav.items.<id>`. */
   label: string;
   keywords?: string[];
 }
 
 export interface NavGroup {
+  /** Message key under `nav.groups` (messages/*.json). */
+  id: string;
   group: string;
   items: NavItem[];
 }
@@ -28,33 +33,37 @@ export interface SettingsSection {
 
 export const NAV: NavGroup[] = [
   {
+    id: 'overview',
     group: 'Overview',
     items: [
-      { href: '/', label: 'Dashboard', keywords: ['home', 'overview', 'dashboard', 'main'] },
-      { href: '/analytics', label: 'Analytics', keywords: ['analytics', 'metrics', 'stats', 'charts'] },
-      { href: '/logs', label: 'Audit Log', keywords: ['audit', 'logs', 'audit log', 'history', 'activity'] },
+      { id: 'dashboard', href: '/', label: 'Dashboard', keywords: ['home', 'overview', 'dashboard', 'main'] },
+      { id: 'analytics', href: '/analytics', label: 'Analytics', keywords: ['analytics', 'metrics', 'stats', 'charts'] },
+      { id: 'auditLog', href: '/logs', label: 'Audit Log', keywords: ['audit', 'logs', 'audit log', 'history', 'activity'] },
     ],
   },
   {
+    id: 'build',
     group: 'Build',
     items: [
-      { href: '/connectors', label: 'Connectors', keywords: ['connectors', 'apis', 'integrations', 'rest', 'soap'] },
-      { href: '/connectors/store', label: 'Marketplace', keywords: ['marketplace', 'store', 'catalog', 'adapters'] },
-      { href: '/mcp-server', label: 'MCP Servers', keywords: ['mcp servers', 'servers', 'mcp', 'tools', 'endpoints'] },
+      { id: 'connectors', href: '/connectors', label: 'Connectors', keywords: ['connectors', 'apis', 'integrations', 'rest', 'soap'] },
+      { id: 'marketplace', href: '/connectors/store', label: 'Marketplace', keywords: ['marketplace', 'store', 'catalog', 'adapters'] },
+      { id: 'mcpServers', href: '/mcp-server', label: 'MCP Servers', keywords: ['mcp servers', 'servers', 'mcp', 'tools', 'endpoints'] },
     ],
   },
   {
+    id: 'intelligence',
     group: 'Intelligence',
     items: [
-      { href: '/knowledge-graph', label: 'Knowledge Graph', keywords: ['knowledge graph', 'kg', 'graph', 'entities'] },
-      { href: '/knowledge-graph/skills', label: 'AI Skills', keywords: ['ai skills', 'skills', 'prompts'] },
-      { href: '/memory', label: 'Memory', keywords: ['memory', 'remember', 'facts', 'preferences', 'knowledge'] },
+      { id: 'knowledgeGraph', href: '/knowledge-graph', label: 'Knowledge Graph', keywords: ['knowledge graph', 'kg', 'graph', 'entities'] },
+      { id: 'aiSkills', href: '/knowledge-graph/skills', label: 'AI Skills', keywords: ['ai skills', 'skills', 'prompts'] },
+      { id: 'memory', href: '/memory', label: 'Memory', keywords: ['memory', 'remember', 'facts', 'preferences', 'knowledge'] },
     ],
   },
   {
+    id: 'getStarted',
     group: 'Get started',
     items: [
-      { href: '/welcome', label: 'Setup & onboarding', keywords: ['setup', 'onboarding', 'welcome', 'getting started', 'guide'] },
+      { id: 'setup', href: '/welcome', label: 'Setup & onboarding', keywords: ['setup', 'onboarding', 'welcome', 'getting started', 'guide'] },
     ],
   },
 ];
diff --git a/packages/frontend/tests/e2e/i18n.spec.ts b/packages/frontend/tests/e2e/i18n.spec.ts
new file mode 100644
index 00000000..150da71e
--- /dev/null
+++ b/packages/frontend/tests/e2e/i18n.spec.ts
@@ -0,0 +1,136 @@
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { expect, test, type Page } from '@playwright/test';
+
+/**
+ * UI language: the amcp_locale cookie wins, then Accept-Language, then English.
+ * Playwright's `locale` option sets the Accept-Language header the server sees.
+ * The session is faked the same way as in redesign.spec.ts.
+ */
+
+const BASE_URL = 'http://localhost:3100';
+
+const USER = {
+  id: 'u1',
+  email: 'test@example.com',
+  name: 'Test User',
+  role: 'ADMIN',
+  organizationId: 'o1',
+  emailVerified: true,
+};
+
+async function fakeSession(page: Page) {
+  await page.context().addCookies([{ name: 'amcp_token', value: 'test-token', url: BASE_URL }]);
+  await page.addInitScript((user) => {
+    localStorage.setItem('amcp_token', 'test-token');
+    localStorage.setItem('amcp_user', JSON.stringify(user));
+  }, USER);
+
+  await page.route(/\/api\//, async (route) => {
+    const url = route.request().url();
+    const json = (body: unknown) =>
+      route.fulfill({ status: 200, contentType: 'application/json', body: JSON.stringify(body) });
+
+    if (url.includes('/api/users/me/onboarding-state')) return json({ onboardingCompletedAt: '2026-01-01T00:00:00Z' });
+    if (url.includes('/api/users/me')) return json(USER);
+    if (url.includes('/api/organizations/current')) return json({ id: 'o1', name: 'Acme', createdAt: '2026-01-01' });
+    if (url.includes('/api/organizations/mine')) return json([{ id: 'o1', name: 'Acme', role: 'ADMIN', joinedAt: '2026-01-01' }]);
+    if (url.includes('/api/license/status')) return json({ plan: 'community', status: 'active' });
+    if (url.includes('/api/connectors')) return json([]);
+    if (url.includes('/api/audit/stats')) return json({ invocations24h: 0, errors24h: 0 });
+    if (url.includes('/api/audit/analytics')) return json({ daily: [], topTools: [], totalInvocations: 0, successRate: 100, avgDuration: 0 });
+    return json({});
+  });
+}
+
+async function expectSidebar(page: Page, lang: string, labels: { group: string; links: string[]; settings: string }) {
+  await expect(page.locator('html')).toHaveAttribute('lang', lang);
+  const aside = page.locator('aside');
+  await expect(aside.getByText(labels.group, { exact: true })).toBeVisible();
+  for (const name of labels.links) {
+    await expect(aside.getByRole('link', { name, exact: true })).toBeVisible();
+  }
+  await expect(aside.getByRole('link', { name: labels.settings, exact: true })).toBeVisible();
+}
+
+test.describe('UI language from Accept-Language', () => {
+  test.describe('de-DE', () => {
+    test.use({ locale: 'de-DE' });
+
+    test('renders the sidebar in German', async ({ page }) => {
+      await fakeSession(page);
+      await page.goto('/');
+      await expectSidebar(page, 'de', {
+        group: 'Übersicht',
+        links: ['Dashboard', 'Audit-Log', 'Marktplatz', 'MCP-Server'],
+        settings: 'Einstellungen',
+      });
+    });
+  });
+
+  test.describe('it-IT', () => {
+    test.use({ locale: 'it-IT' });
+
+    test('renders the sidebar in Italian', async ({ page }) => {
+      await fakeSession(page);
+      await page.goto('/');
+      await expectSidebar(page, 'it', {
+        group: 'Panoramica',
+        links: ['Dashboard', 'Registro di audit', 'Connettori', 'Server MCP'],
+        settings: 'Impostazioni',
+      });
+    });
+  });
+
+  test.describe('fr-FR', () => {
+    test.use({ locale: 'fr-FR' });
+
+    test('falls back to English for an unsupported language', async ({ page }) => {
+      await fakeSession(page);
+      await page.goto('/');
+      await expectSidebar(page, 'en', {
+        group: 'Overview',
+        links: ['Dashboard', 'Audit Log', 'Marketplace', 'MCP Servers'],
+        settings: 'Settings',
+      });
+    });
+  });
+});
+
+test.describe('amcp_locale cookie', () => {
+  test.use({ locale: 'de-DE' });
+
+  test('takes precedence over Accept-Language', async ({ page }) => {
+    await page.context().addCookies([{ name: 'amcp_locale', value: 'it', url: BASE_URL }]);
+    await fakeSession(page);
+    await page.goto('/');
+    await expectSidebar(page, 'it', { group: 'Panoramica', links: ['Connettori'], settings: 'Impostazioni' });
+  });
+
+  test('is ignored when it holds an unsupported locale', async ({ page }) => {
+    await page.context().addCookies([{ name: 'amcp_locale', value: 'xx', url: BASE_URL }]);
+    await fakeSession(page);
+    await page.goto('/');
+    await expectSidebar(page, 'de', { group: 'Übersicht', links: ['Marktplatz'], settings: 'Einstellungen' });
+  });
+});
+
+test.describe('message files', () => {
+  const read = (locale: string) =>
+    JSON.parse(readFileSync(join(__dirname, '../../messages', `${locale}.json`), 'utf8')) as Record<string, unknown>;
+
+  const keys = (messages: Record<string, unknown>, prefix = ''): string[] =>
+    Object.entries(messages).flatMap(([key, value]) =>
+      value && typeof value === 'object'
+        ? keys(value as Record<string, unknown>, `${prefix}${key}.`)
+        : [`${prefix}${key}`]
+    );
+
+  const english = keys(read('en')).sort();
+
+  for (const locale of ['de', 'it']) {
+    test(`${locale}.json has exactly the keys of en.json`, () => {
+      expect(keys(read(locale)).sort()).toEqual(english);
+    });
+  }
+});