diff --git a/packages/backend/src/adapters/adapters.controller.ts b/packages/backend/src/adapters/adapters.controller.ts
index 4661b015..749cfba4 100644
--- a/packages/backend/src/adapters/adapters.controller.ts
+++ b/packages/backend/src/adapters/adapters.controller.ts
@@ -78,6 +78,29 @@ export class AdaptersPublicController {
     res.type('application/json').send(body);
   }
 
+  // Two path segments, so the authenticated `GET :slug` never sees it.
+  @Get('ranking/installs')
+  @ApiOperation({
+    summary: 'Listed adapters, most-installed first',
+    description:
+      'The slugs of listed adapters ordered by how many workspaces on this deployment have them installed, ' +
+      'for the marketing website to order its marketplace and guides. Only the order is returned, never a count; ' +
+      'adapters installed by fewer than 3 workspaces are left out. Public.',
+  })
+  async installRanking(
+    @Headers('if-none-match') ifNoneMatch: string | undefined,
+    @Res() res: Response,
+  ) {
+    const { body, etag } = await this.adaptersService.installRanking();
+    res.setHeader('ETag', etag);
+    res.setHeader('Cache-Control', PUBLIC_CATALOG_CACHE_CONTROL);
+    if (etagMatches(ifNoneMatch, etag)) {
+      res.status(304).end();
+      return;
+    }
+    res.type('application/json').send(body);
+  }
+
   // Two path segments, so the authenticated `GET :slug` never sees it.
   @Get(':slug/instructions')
   @ApiOperation({
diff --git a/packages/backend/src/adapters/adapters.service.spec.ts b/packages/backend/src/adapters/adapters.service.spec.ts
index cf4dc615..357a00a5 100644
--- a/packages/backend/src/adapters/adapters.service.spec.ts
+++ b/packages/backend/src/adapters/adapters.service.spec.ts
@@ -847,6 +847,57 @@ describe('AdaptersService popular connectors', () => {
   });
 });
 
+describe('AdaptersService install ranking', () => {
+  function service(opts: { rows?: Array<{ slug: string | null }>; fail?: boolean } = {}) {
+    const svc = Object.create(AdaptersService.prototype) as AdaptersService;
+    (svc as any).logger = { warn: jest.fn() };
+    (svc as any).configService = { get: (k: string) => (k === 'DEPLOYMENT_MODE' ? 'cloud' : undefined) };
+    const queryRaw = opts.fail
+      ? jest.fn().mockRejectedValue(new Error('db down'))
+      : jest.fn().mockResolvedValue(opts.rows ?? []);
+    (svc as any).prisma = { $queryRaw: queryRaw };
+    return { svc, queryRaw };
+  }
+  const slugsOf = async (svc: AdaptersService) => JSON.parse((await svc.installRanking()).body).slugs;
+
+  it('keeps the order of the query, which ranks by installing workspaces', async () => {
+    const { svc } = service({ rows: [{ slug: 'telegram-bot' }, { slug: 'etsy' }, { slug: 'odoo' }] });
+    expect(await slugsOf(svc)).toEqual(['telegram-bot', 'etsy', 'odoo']);
+  });
+
+  it('sends only slugs, never a count, and asks for three workspaces that used it', async () => {
+    const { svc, queryRaw } = service({ rows: [{ slug: 'etsy' }] });
+    expect(JSON.parse((await svc.installRanking()).body)).toEqual({ slugs: ['etsy'] });
+    const [sql, ...values] = queryRaw.mock.calls[0];
+    expect(sql.join('?')).toMatch(/ti\.connector_id = c\.id AND ti\.status = 'SUCCESS'/);
+    expect(sql.join('?')).toMatch(/HAVING COUNT\(DISTINCT c\.organization_id\) >= \?/);
+    expect(values).toEqual([3]);
+  });
+
+  it('leaves out adapters that are not listed here (self-host only on the cloud, unknown, null)', async () => {
+    const { svc } = service({ rows: [{ slug: 'etsy' }, { slug: 'no-such-adapter' }, { slug: 'idealista' }, { slug: null }] });
+    expect(await slugsOf(svc)).toEqual(['etsy']);
+  });
+
+  it('ranks once per cache window, not on every request', async () => {
+    const { svc, queryRaw } = service({ rows: [{ slug: 'etsy' }] });
+    await svc.installRanking();
+    await svc.installRanking();
+    expect(queryRaw).toHaveBeenCalledTimes(1);
+  });
+
+  it('serves the last good ranking when the query fails, and an empty one before any', async () => {
+    const { svc } = service({ fail: true });
+    expect(await slugsOf(svc)).toEqual([]);
+
+    const ok = service({ rows: [{ slug: 'etsy' }] });
+    await ok.svc.installRanking();
+    (ok.svc as any).installRankingCache.at = 0;
+    (ok.svc as any).prisma.$queryRaw = jest.fn().mockRejectedValue(new Error('db down'));
+    expect(await slugsOf(ok.svc)).toEqual(['etsy']);
+  });
+});
+
 describe('sap-s4hana-cloud: token URL and refused client credentials', () => {
   const adapter = require('./intl/sap-s4hana-cloud.json');
 
diff --git a/packages/backend/src/adapters/adapters.service.ts b/packages/backend/src/adapters/adapters.service.ts
index 11b045fe..eb8fb233 100644
--- a/packages/backend/src/adapters/adapters.service.ts
+++ b/packages/backend/src/adapters/adapters.service.ts
@@ -30,6 +30,7 @@ import {
   POPULAR_MIN_WORKSPACES,
   POPULAR_WINDOW_DAYS,
 } from './popular-connectors';
+import { INSTALL_RANKING_CACHE_MS, INSTALL_RANKING_MIN_WORKSPACES } from './install-ranking';
 import { ConnectorsService } from '../connectors/connectors.service';
 import { classifyToolExecutionError } from '../connectors/connector-error.util';
 import { applyResponseTransform } from '../connectors/response-transform.util';
@@ -248,6 +249,45 @@ export class AdaptersService {
     return slugs;
   }
 
+  private installRankingCache: { at: number; ranking: SerializedBody } | null = null;
+
+  /**
+   * `{ slugs }`: the listed adapters, most-installed first, as a ready-to-send
+   * body (see ./install-ranking.ts). Cached for six hours; when the query
+   * fails, the last good ranking (or an empty one) is served and the next
+   * request tries again.
+   */
+  async installRanking(): Promise<SerializedBody> {
+    const now = Date.now();
+    const cached = this.installRankingCache;
+    if (cached && now - cached.at < INSTALL_RANKING_CACHE_MS) return cached.ranking;
+    try {
+      // The EXISTS goes through tool_invocations' (connector_id, created_at)
+      // index and stops at the first successful call of each connector.
+      const rows = await this.prisma.$queryRaw<Array<{ slug: string | null }>>`
+        SELECT c.config->>'adapterSlug' AS slug
+        FROM connectors c
+        WHERE c.config ? 'adapterSlug'
+          AND EXISTS (
+            SELECT 1 FROM tool_invocations ti
+            WHERE ti.connector_id = c.id AND ti.status = 'SUCCESS'
+          )
+        GROUP BY 1
+        HAVING COUNT(DISTINCT c.organization_id) >= ${INSTALL_RANKING_MIN_WORKSPACES}
+        ORDER BY COUNT(DISTINCT c.organization_id) DESC, 1`;
+      const listed = new Set(this.listAll().map((a) => a.slug));
+      const slugs = rows
+        .map((r) => r.slug)
+        .filter((s): s is string => typeof s === 'string' && listed.has(s));
+      const ranking = serializeWithEtag({ slugs });
+      this.installRankingCache = { at: now, ranking };
+      return ranking;
+    } catch (err: any) {
+      this.logger.warn(`Could not rank adapters by installs: ${err?.message ?? err}`);
+      return cached?.ranking ?? serializeWithEtag({ slugs: [] });
+    }
+  }
+
   /** Catalog slugs this workspace already has a connector for. */
   async installedAdapterSlugs(organizationId: string): Promise<Set<string>> {
     const rows = await this.prisma.connector.findMany({
diff --git a/packages/backend/src/adapters/install-ranking.ts b/packages/backend/src/adapters/install-ranking.ts
new file mode 100644
index 00000000..5f40139c
--- /dev/null
+++ b/packages/backend/src/adapters/install-ranking.ts
@@ -0,0 +1,17 @@
+/**
+ * The catalog in install order, for the website: its connector marketplace
+ * and its guides lead with the connectors most workspaces install, instead of
+ * the newest guide or the longest tool list.
+ *
+ * Ranked from this deployment's own data: how many workspaces have a
+ * connector installed from the adapter today that has answered at least one
+ * call (one workspace with five Odoo connectors counts once). A connector
+ * installed and never used, as in the free starter pack many sign-ups add in
+ * one click, does not count. Only the order leaves the server, never a count,
+ * and an adapter needs MIN_WORKSPACES workspaces before it is ranked, so one
+ * tenant's choice never shows through. Adapters below that, and every adapter
+ * on a fresh self-host with no data, are left to the caller's own order.
+ */
+export const INSTALL_RANKING_MIN_WORKSPACES = 3;
+/** Installs move slowly and the website caches for a day anyway. */
+export const INSTALL_RANKING_CACHE_MS = 6 * 60 * 60 * 1000;