diff --git a/src/app/api/users/[username]/followers/route.test.ts b/src/app/api/users/[username]/followers/route.test.ts
new file mode 100644
index 00000000..0b42b4f3
--- /dev/null
+++ b/src/app/api/users/[username]/followers/route.test.ts
@@ -0,0 +1,107 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { NextRequest } from "next/server";
+import { GET } from "./route";
+
+const mockFrom = vi.fn();
+
+const supabaseClient = {
+  from: mockFrom,
+};
+
+vi.mock("@/lib/supabase/server", () => ({
+  createClient: vi.fn(() => Promise.resolve(supabaseClient)),
+}));
+
+function makeRequest(searchParams?: Record<string, string>) {
+  let url = "http://localhost/api/users/testuser/followers";
+  if (searchParams) {
+    url += `?${new URLSearchParams(searchParams).toString()}`;
+  }
+  return new NextRequest(url, { method: "GET" });
+}
+
+const routeParams = { params: Promise.resolve({ username: "testuser" }) };
+
+function profileChain(result: { data: unknown; error: unknown }) {
+  const chain: Record<string, ReturnType<typeof vi.fn>> = {};
+  for (const method of ["select", "eq", "single"]) {
+    chain[method] = vi.fn().mockReturnValue(chain);
+  }
+  chain.single.mockResolvedValue(result);
+  return chain;
+}
+
+function followsChain(result: { data: unknown[]; error: unknown; count: number }) {
+  const chain: Record<string, ReturnType<typeof vi.fn>> = {};
+  for (const method of ["select", "eq", "order", "range"]) {
+    chain[method] = vi.fn().mockReturnValue(chain);
+  }
+  chain.range.mockResolvedValue(result);
+  return chain;
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+});
+
+describe("GET /api/users/[username]/followers", () => {
+  it("returns 404 when user is not found", async () => {
+    mockFrom.mockReturnValue(profileChain({ data: null, error: { message: "not found" } }));
+
+    const res = await GET(makeRequest(), routeParams);
+
+    expect(res.status).toBe(404);
+  });
+
+  it("falls back for invalid pagination params", async () => {
+    const targetProfile = profileChain({ data: { id: "user-123" }, error: null });
+    const follows = followsChain({ data: [], error: null, count: 0 });
+
+    let callCount = 0;
+    mockFrom.mockImplementation(() => {
+      callCount++;
+      return callCount === 1 ? targetProfile : follows;
+    });
+
+    const res = await GET(
+      makeRequest({ limit: "0", offset: "-10" }),
+      routeParams
+    );
+    const json = await res.json();
+
+    expect(res.status).toBe(200);
+    expect(follows.range).toHaveBeenCalledWith(0, 19);
+    expect(json.pagination.limit).toBe(20);
+    expect(json.pagination.offset).toBe(0);
+  });
+
+  it("caps large limits", async () => {
+    const targetProfile = profileChain({ data: { id: "user-123" }, error: null });
+    const follows = followsChain({ data: [], error: null, count: 0 });
+
+    let callCount = 0;
+    mockFrom.mockImplementation(() => {
+      callCount++;
+      return callCount === 1 ? targetProfile : follows;
+    });
+
+    await GET(makeRequest({ limit: "500", offset: "5" }), routeParams);
+
+    expect(follows.range).toHaveBeenCalledWith(5, 104);
+  });
+
+  it("keeps valid pagination params", async () => {
+    const targetProfile = profileChain({ data: { id: "user-123" }, error: null });
+    const follows = followsChain({ data: [], error: null, count: 0 });
+
+    let callCount = 0;
+    mockFrom.mockImplementation(() => {
+      callCount++;
+      return callCount === 1 ? targetProfile : follows;
+    });
+
+    await GET(makeRequest({ limit: "10", offset: "30" }), routeParams);
+
+    expect(follows.range).toHaveBeenCalledWith(30, 39);
+  });
+});
diff --git a/src/app/api/users/[username]/followers/route.ts b/src/app/api/users/[username]/followers/route.ts
index ba6c35aa..b9a4adfc 100644
--- a/src/app/api/users/[username]/followers/route.ts
+++ b/src/app/api/users/[username]/followers/route.ts
@@ -1,76 +1,92 @@
-import { NextRequest, NextResponse } from "next/server";
-import { createClient } from "@/lib/supabase/server";
-
-// GET /api/users/[username]/followers — list a user's followers
-export async function GET(
-  request: NextRequest,
-  { params }: { params: Promise<{ username: string }> }
-) {
-  try {
-    const { username } = await params;
-    const supabase = await createClient();
-    const searchParams = request.nextUrl.searchParams;
-    const limit = Math.min(Number(searchParams.get("limit")) || 20, 100);
-    const offset = Number(searchParams.get("offset")) || 0;
-
-    // Look up target user
-    const { data: targetProfile, error: profileError } = await supabase
-      .from("profiles")
-      .select("id")
-      .eq("username", username)
-      .single();
-
-    if (profileError || !targetProfile) {
-      return NextResponse.json({ error: "User not found" }, { status: 404 });
-    }
-
-    // Get followers with profile details
-    const { data: follows, error, count } = await supabase
-      .from("follows")
-      .select(
-        `
-        id,
-        created_at,
-        follower:profiles!follower_id (
-          id,
-          username,
-          full_name,
-          avatar_url,
-          bio,
-          is_available,
-          account_type,
-          verified,
-          verification_type
-        )
-      `,
-        { count: "exact" }
-      )
-      .eq("following_id", targetProfile.id)
-      .order("created_at", { ascending: false })
-      .range(offset, offset + limit - 1);
-
-    if (error) {
-      return NextResponse.json({ error: error.message }, { status: 400 });
-    }
-
-    // Flatten: extract the profile from each follow record
-    const followers = (follows || []).map((f) => ({
-      ...f.follower,
-      followed_at: f.created_at,
-    }));
-
-    return NextResponse.json({
-      data: followers,
-      pagination: {
-        total: count || 0,
-        limit,
-        offset,
-      },
-    });
-  } catch {
-    return NextResponse.json(
-      { error: "An unexpected error occurred" },
-      { status: 500 }
-    );
-  }
-}
+import { NextRequest, NextResponse } from "next/server";
+import { createClient } from "@/lib/supabase/server";
+
+function parsePositiveInt(value: string | null, fallback: number, max: number): number {
+  const parsed = Number.parseInt(value ?? "", 10);
+  if (!Number.isFinite(parsed) || parsed <= 0) {
+    return fallback;
+  }
+  return Math.min(parsed, max);
+}
+
+function parseNonNegativeInt(value: string | null, fallback: number): number {
+  const parsed = Number.parseInt(value ?? "", 10);
+  if (!Number.isFinite(parsed) || parsed < 0) {
+    return fallback;
+  }
+  return parsed;
+}
+
+// GET /api/users/[username]/followers - list a user's followers
+export async function GET(
+  request: NextRequest,
+  { params }: { params: Promise<{ username: string }> }
+) {
+  try {
+    const { username } = await params;
+    const supabase = await createClient();
+    const searchParams = request.nextUrl.searchParams;
+    const limit = parsePositiveInt(searchParams.get("limit"), 20, 100);
+    const offset = parseNonNegativeInt(searchParams.get("offset"), 0);
+
+    // Look up target user
+    const { data: targetProfile, error: profileError } = await supabase
+      .from("profiles")
+      .select("id")
+      .eq("username", username)
+      .single();
+
+    if (profileError || !targetProfile) {
+      return NextResponse.json({ error: "User not found" }, { status: 404 });
+    }
+
+    // Get followers with profile details
+    const { data: follows, error, count } = await supabase
+      .from("follows")
+      .select(
+        `
+        id,
+        created_at,
+        follower:profiles!follower_id (
+          id,
+          username,
+          full_name,
+          avatar_url,
+          bio,
+          is_available,
+          account_type,
+          verified,
+          verification_type
+        )
+      `,
+        { count: "exact" }
+      )
+      .eq("following_id", targetProfile.id)
+      .order("created_at", { ascending: false })
+      .range(offset, offset + limit - 1);
+
+    if (error) {
+      return NextResponse.json({ error: error.message }, { status: 400 });
+    }
+
+    // Flatten: extract the profile from each follow record
+    const followers = (follows || []).map((f) => ({
+      ...f.follower,
+      followed_at: f.created_at,
+    }));
+
+    return NextResponse.json({
+      data: followers,
+      pagination: {
+        total: count || 0,
+        limit,
+        offset,
+      },
+    });
+  } catch {
+    return NextResponse.json(
+      { error: "An unexpected error occurred" },
+      { status: 500 }
+    );
+  }
+}
diff --git a/src/app/api/users/[username]/following/route.test.ts b/src/app/api/users/[username]/following/route.test.ts
new file mode 100644
index 00000000..ecab1833
--- /dev/null
+++ b/src/app/api/users/[username]/following/route.test.ts
@@ -0,0 +1,107 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { NextRequest } from "next/server";
+import { GET } from "./route";
+
+const mockFrom = vi.fn();
+
+const supabaseClient = {
+  from: mockFrom,
+};
+
+vi.mock("@/lib/supabase/server", () => ({
+  createClient: vi.fn(() => Promise.resolve(supabaseClient)),
+}));
+
+function makeRequest(searchParams?: Record<string, string>) {
+  let url = "http://localhost/api/users/testuser/following";
+  if (searchParams) {
+    url += `?${new URLSearchParams(searchParams).toString()}`;
+  }
+  return new NextRequest(url, { method: "GET" });
+}
+
+const routeParams = { params: Promise.resolve({ username: "testuser" }) };
+
+function profileChain(result: { data: unknown; error: unknown }) {
+  const chain: Record<string, ReturnType<typeof vi.fn>> = {};
+  for (const method of ["select", "eq", "single"]) {
+    chain[method] = vi.fn().mockReturnValue(chain);
+  }
+  chain.single.mockResolvedValue(result);
+  return chain;
+}
+
+function followsChain(result: { data: unknown[]; error: unknown; count: number }) {
+  const chain: Record<string, ReturnType<typeof vi.fn>> = {};
+  for (const method of ["select", "eq", "order", "range"]) {
+    chain[method] = vi.fn().mockReturnValue(chain);
+  }
+  chain.range.mockResolvedValue(result);
+  return chain;
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+});
+
+describe("GET /api/users/[username]/following", () => {
+  it("returns 404 when user is not found", async () => {
+    mockFrom.mockReturnValue(profileChain({ data: null, error: { message: "not found" } }));
+
+    const res = await GET(makeRequest(), routeParams);
+
+    expect(res.status).toBe(404);
+  });
+
+  it("falls back for invalid pagination params", async () => {
+    const targetProfile = profileChain({ data: { id: "user-123" }, error: null });
+    const follows = followsChain({ data: [], error: null, count: 0 });
+
+    let callCount = 0;
+    mockFrom.mockImplementation(() => {
+      callCount++;
+      return callCount === 1 ? targetProfile : follows;
+    });
+
+    const res = await GET(
+      makeRequest({ limit: "-5", offset: "-10" }),
+      routeParams
+    );
+    const json = await res.json();
+
+    expect(res.status).toBe(200);
+    expect(follows.range).toHaveBeenCalledWith(0, 19);
+    expect(json.pagination.limit).toBe(20);
+    expect(json.pagination.offset).toBe(0);
+  });
+
+  it("caps large limits", async () => {
+    const targetProfile = profileChain({ data: { id: "user-123" }, error: null });
+    const follows = followsChain({ data: [], error: null, count: 0 });
+
+    let callCount = 0;
+    mockFrom.mockImplementation(() => {
+      callCount++;
+      return callCount === 1 ? targetProfile : follows;
+    });
+
+    await GET(makeRequest({ limit: "500", offset: "5" }), routeParams);
+
+    expect(follows.range).toHaveBeenCalledWith(5, 104);
+  });
+
+  it("keeps valid pagination params", async () => {
+    const targetProfile = profileChain({ data: { id: "user-123" }, error: null });
+    const follows = followsChain({ data: [], error: null, count: 0 });
+
+    let callCount = 0;
+    mockFrom.mockImplementation(() => {
+      callCount++;
+      return callCount === 1 ? targetProfile : follows;
+    });
+
+    await GET(makeRequest({ limit: "10", offset: "30" }), routeParams);
+
+    expect(follows.range).toHaveBeenCalledWith(30, 39);
+  });
+});
diff --git a/src/app/api/users/[username]/following/route.ts b/src/app/api/users/[username]/following/route.ts
index fa5fdaf4..855d4ef7 100644
--- a/src/app/api/users/[username]/following/route.ts
+++ b/src/app/api/users/[username]/following/route.ts
@@ -1,76 +1,92 @@
-import { NextRequest, NextResponse } from "next/server";
-import { createClient } from "@/lib/supabase/server";
-
-// GET /api/users/[username]/following — list who a user follows
-export async function GET(
-  request: NextRequest,
-  { params }: { params: Promise<{ username: string }> }
-) {
-  try {
-    const { username } = await params;
-    const supabase = await createClient();
-    const searchParams = request.nextUrl.searchParams;
-    const limit = Math.min(Number(searchParams.get("limit")) || 20, 100);
-    const offset = Number(searchParams.get("offset")) || 0;
-
-    // Look up target user
-    const { data: targetProfile, error: profileError } = await supabase
-      .from("profiles")
-      .select("id")
-      .eq("username", username)
-      .single();
-
-    if (profileError || !targetProfile) {
-      return NextResponse.json({ error: "User not found" }, { status: 404 });
-    }
-
-    // Get following with profile details
-    const { data: follows, error, count } = await supabase
-      .from("follows")
-      .select(
-        `
-        id,
-        created_at,
-        following:profiles!following_id (
-          id,
-          username,
-          full_name,
-          avatar_url,
-          bio,
-          is_available,
-          account_type,
-          verified,
-          verification_type
-        )
-      `,
-        { count: "exact" }
-      )
-      .eq("follower_id", targetProfile.id)
-      .order("created_at", { ascending: false })
-      .range(offset, offset + limit - 1);
-
-    if (error) {
-      return NextResponse.json({ error: error.message }, { status: 400 });
-    }
-
-    // Flatten: extract the profile from each follow record
-    const following = (follows || []).map((f) => ({
-      ...f.following,
-      followed_at: f.created_at,
-    }));
-
-    return NextResponse.json({
-      data: following,
-      pagination: {
-        total: count || 0,
-        limit,
-        offset,
-      },
-    });
-  } catch {
-    return NextResponse.json(
-      { error: "An unexpected error occurred" },
-      { status: 500 }
-    );
-  }
-}
+import { NextRequest, NextResponse } from "next/server";
+import { createClient } from "@/lib/supabase/server";
+
+function parsePositiveInt(value: string | null, fallback: number, max: number): number {
+  const parsed = Number.parseInt(value ?? "", 10);
+  if (!Number.isFinite(parsed) || parsed <= 0) {
+    return fallback;
+  }
+  return Math.min(parsed, max);
+}
+
+function parseNonNegativeInt(value: string | null, fallback: number): number {
+  const parsed = Number.parseInt(value ?? "", 10);
+  if (!Number.isFinite(parsed) || parsed < 0) {
+    return fallback;
+  }
+  return parsed;
+}
+
+// GET /api/users/[username]/following - list who a user follows
+export async function GET(
+  request: NextRequest,
+  { params }: { params: Promise<{ username: string }> }
+) {
+  try {
+    const { username } = await params;
+    const supabase = await createClient();
+    const searchParams = request.nextUrl.searchParams;
+    const limit = parsePositiveInt(searchParams.get("limit"), 20, 100);
+    const offset = parseNonNegativeInt(searchParams.get("offset"), 0);
+
+    // Look up target user
+    const { data: targetProfile, error: profileError } = await supabase
+      .from("profiles")
+      .select("id")
+      .eq("username", username)
+      .single();
+
+    if (profileError || !targetProfile) {
+      return NextResponse.json({ error: "User not found" }, { status: 404 });
+    }
+
+    // Get following with profile details
+    const { data: follows, error, count } = await supabase
+      .from("follows")
+      .select(
+        `
+        id,
+        created_at,
+        following:profiles!following_id (
+          id,
+          username,
+          full_name,
+          avatar_url,
+          bio,
+          is_available,
+          account_type,
+          verified,
+          verification_type
+        )
+      `,
+        { count: "exact" }
+      )
+      .eq("follower_id", targetProfile.id)
+      .order("created_at", { ascending: false })
+      .range(offset, offset + limit - 1);
+
+    if (error) {
+      return NextResponse.json({ error: error.message }, { status: 400 });
+    }
+
+    // Flatten: extract the profile from each follow record
+    const following = (follows || []).map((f) => ({
+      ...f.following,
+      followed_at: f.created_at,
+    }));
+
+    return NextResponse.json({
+      data: following,
+      pagination: {
+        total: count || 0,
+        limit,
+        offset,
+      },
+    });
+  } catch {
+    return NextResponse.json(
+      { error: "An unexpected error occurred" },
+      { status: 500 }
+    );
+  }
+}