diff --git a/CHANGES.md b/CHANGES.md
index e8539f6a..b1c1db0a 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -144,6 +144,11 @@ To be released.
     editor and is now returned from `GET /api/v1/preferences`, which helps
     clients like Phanpy honor each account's preferred CW behavior.  [[#425]]
 
+ -  Fixed Mastodon API compatibility for clients such as the official Mastodon
+    iOS app by returning empty arrays for unimplemented trends and suggestions
+    endpoints instead of `404 Not Found` responses.  The suggestions endpoints
+    still require an authenticated user token.  [[#421], [#427] by Vignesh]
+
  -  Added a new dashboard page for thumbnail cleanup at `/thumbnail_cleanup`.
     Thumbnails from remote posts that have not been bookmarked, liked, reacted
     to, shared nor quoted by a local account before a given cut-off data can
@@ -159,8 +164,10 @@ To be released.
 [#357]: https://github.com/fedify-dev/hollo/issues/357
 [#409]: https://github.com/fedify-dev/hollo/issues/409
 [#420]: https://github.com/fedify-dev/hollo/issues/420
+[#421]: https://github.com/fedify-dev/hollo/issues/421
 [#424]: https://github.com/fedify-dev/hollo/issues/424
 [#425]: https://github.com/fedify-dev/hollo/issues/425
+[#427]: https://github.com/fedify-dev/hollo/pull/427
 [#435]: https://github.com/fedify-dev/hollo/issues/435
 [#436]: https://github.com/fedify-dev/hollo/pull/436
 [#445]: https://github.com/fedify-dev/hollo/issues/445
diff --git a/src/api/stub-endpoints.test.ts b/src/api/stub-endpoints.test.ts
new file mode 100644
index 00000000..7d46a797
--- /dev/null
+++ b/src/api/stub-endpoints.test.ts
@@ -0,0 +1,89 @@
+import { beforeEach, describe, expect, it } from "vitest";
+
+import { cleanDatabase } from "../../tests/helpers";
+import {
+  bearerAuthorization,
+  createAccount,
+  createOAuthApplication,
+  getAccessToken,
+  type Token,
+} from "../../tests/helpers/oauth";
+import app from "../index";
+
+describe.sequential("Mastodon compatibility stub endpoints", () => {
+  let readAccountsToken: Token;
+  let readSearchToken: Token;
+
+  beforeEach(async () => {
+    await cleanDatabase();
+
+    const account = await createAccount();
+    const client = await createOAuthApplication({
+      scopes: ["read:accounts", "read:search"],
+    });
+    readAccountsToken = await getAccessToken(client, account, [
+      "read:accounts",
+    ]);
+    readSearchToken = await getAccessToken(client, account, ["read:search"]);
+  });
+
+  it.each([
+    "/api/v1/trends",
+    "/api/v1/trends/tags",
+    "/api/v1/trends/statuses?offset=0",
+    "/api/v1/trends/links",
+  ])("returns an empty array for GET %s", async (path) => {
+    expect.assertions(3);
+
+    const response = await app.request(path);
+
+    expect(response.status).toBe(200);
+    expect(response.headers.get("content-type")).toBe("application/json");
+    expect(await response.json()).toEqual([]);
+  });
+
+  it.each(["/api/v1/suggestions", "/api/v2/suggestions"])(
+    "requires authentication for GET %s",
+    async (path) => {
+      expect.assertions(2);
+
+      const response = await app.request(path);
+
+      expect(response.status).toBe(401);
+      expect(await response.json()).toEqual({ error: "unauthorized" });
+    },
+  );
+
+  it.each(["/api/v1/suggestions", "/api/v2/suggestions"])(
+    "rejects insufficient scope for GET %s",
+    async (path) => {
+      expect.assertions(2);
+
+      const response = await app.request(path, {
+        headers: {
+          authorization: bearerAuthorization(readSearchToken),
+        },
+      });
+
+      expect(response.status).toBe(403);
+      expect(await response.json()).toEqual({ error: "insufficient_scope" });
+    },
+  );
+
+  it.each(["/api/v1/suggestions", "/api/v2/suggestions"])(
+    "returns an empty array for GET %s",
+    async (path) => {
+      expect.assertions(3);
+
+      const response = await app.request(path, {
+        headers: {
+          authorization: bearerAuthorization(readAccountsToken),
+        },
+      });
+
+      expect(response.status).toBe(200);
+      expect(response.headers.get("content-type")).toBe("application/json");
+      expect(await response.json()).toEqual([]);
+    },
+  );
+});
diff --git a/src/api/v1/index.ts b/src/api/v1/index.ts
index d2d6db4b..87045bc9 100644
--- a/src/api/v1/index.ts
+++ b/src/api/v1/index.ts
@@ -92,6 +92,33 @@ app.get("/announcements", (c) => {
   return c.json([]);
 });
 
+app.get("/trends/tags", (c) => {
+  return c.json([]);
+});
+
+app.get("/trends/statuses", (c) => {
+  return c.json([]);
+});
+
+app.get("/trends/links", (c) => {
+  return c.json([]);
+});
+
+// Mastodon clients also request /trends without a subpath,
+// which is equivalent to /trends/tags:
+app.get("/trends", (c) => {
+  return c.json([]);
+});
+
+app.get(
+  "/suggestions",
+  tokenRequired,
+  scopeRequired(["read:accounts"]),
+  (c) => {
+    return c.json([]);
+  },
+);
+
 app.get(
   "/favourites",
   tokenRequired,
diff --git a/src/api/v1/timelines.test.ts b/src/api/v1/timelines.test.ts
index 04fe105a..57b379c5 100644
--- a/src/api/v1/timelines.test.ts
+++ b/src/api/v1/timelines.test.ts
@@ -142,7 +142,6 @@ describe.sequential("/api/v1/timelines/list/:list_id", () => {
     expect(json[0].media_attachments[0].type).toBe("unknown");
   });
 });
-
 describe.sequential("/api/v1/timelines/home", () => {
   let owner: Awaited<ReturnType<typeof createAccount>>;
   let approvedAuthor: Awaited<ReturnType<typeof createAccount>>;
@@ -222,3 +221,95 @@ describe.sequential("/api/v1/timelines/home", () => {
     expect(ids).toEqual([approvedPostId]);
   });
 });
+
+describe.sequential("/api/v1/timelines/home", () => {
+  let owner: Awaited<ReturnType<typeof createAccount>>;
+  let client: Awaited<ReturnType<typeof createOAuthApplication>>;
+  let accessToken: Awaited<ReturnType<typeof getAccessToken>>;
+
+  beforeEach(async () => {
+    await cleanDatabase();
+
+    owner = await createAccount();
+    client = await createOAuthApplication({
+      scopes: ["read:statuses"],
+    });
+    accessToken = await getAccessToken(client, owner, ["read:statuses"]);
+  });
+
+  it("serializes quotes using the Mastodon Quote entity format", async () => {
+    expect.assertions(7);
+
+    const authorId = crypto.randomUUID() as Uuid;
+    const quotedPostId = uuidv7();
+    const quotePostId = uuidv7();
+
+    await db
+      .insert(instances)
+      .values({ host: "remote.test" })
+      .onConflictDoNothing();
+
+    await db.insert(accounts).values({
+      id: authorId,
+      iri: "https://remote.test/users/author",
+      instanceHost: "remote.test",
+      type: "Person",
+      name: "Remote author",
+      emojis: {},
+      handle: "@author@remote.test",
+      bioHtml: "",
+      url: "https://remote.test/@author",
+      protected: false,
+      inboxUrl: "https://remote.test/users/author/inbox",
+    });
+
+    await db.insert(follows).values({
+      iri: "https://hollo.test/follows/author",
+      followingId: authorId,
+      followerId: owner.id,
+      approved: new Date(),
+    });
+
+    await db.insert(posts).values([
+      {
+        id: quotedPostId,
+        iri: `https://remote.test/notes/${quotedPostId}`,
+        type: "Note",
+        accountId: authorId,
+        visibility: "public",
+        content: "Quoted post",
+        contentHtml: "<p>Quoted post</p>",
+        published: new Date(),
+      },
+      {
+        id: quotePostId,
+        iri: `https://remote.test/notes/${quotePostId}`,
+        type: "Note",
+        accountId: authorId,
+        quoteTargetId: quotedPostId,
+        visibility: "public",
+        content: "Quote post",
+        contentHtml: "<p>Quote post</p>",
+        published: new Date(),
+      },
+    ]);
+
+    const response = await app.request("/api/v1/timelines/home", {
+      method: "GET",
+      headers: {
+        authorization: bearerAuthorization(accessToken),
+      },
+    });
+
+    expect(response.status).toBe(200);
+    expect(response.headers.get("content-type")).toBe("application/json");
+
+    const json = await response.json();
+
+    expect(Array.isArray(json)).toBe(true);
+    expect(json[0].id).toBe(quotePostId);
+    expect(json[0].quote_id).toBe(quotedPostId);
+    expect(json[0].quote.state).toBe("accepted");
+    expect(json[0].quote.quoted_status.id).toBe(quotedPostId);
+  });
+});
diff --git a/src/api/v2/index.ts b/src/api/v2/index.ts
index d1016d2b..a0557040 100644
--- a/src/api/v2/index.ts
+++ b/src/api/v2/index.ts
@@ -47,6 +47,15 @@ app.route("/notifications", notificationsRoutes);
 
 app.post("/media", tokenRequired, scopeRequired(["write:media"]), postMedia);
 
+app.get(
+  "/suggestions",
+  tokenRequired,
+  scopeRequired(["read:accounts"]),
+  (c) => {
+    return c.json([]);
+  },
+);
+
 app.get(
   "/search",
   tokenRequired,