diff --git a/src/middleware/rateLimit.js b/src/middleware/rateLimit.js
new file mode 100644
index 0000000..acac0f1
--- /dev/null
+++ b/src/middleware/rateLimit.js
@@ -0,0 +1,16 @@
+// Fixed-window rate limiter. Windows start at multiples of windowMs.
+export function createRateLimiter({ limit, windowMs, now = Date.now }) {
+  const hits = new Map(); // key -> { window, count }
+
+  return function allow(key) {
+    const window = Math.floor(now() / windowMs);
+    const entry = hits.get(key);
+    if (!entry || entry.window !== window) {
+      hits.set(key, { window, count: 1 });
+      return limit >= 1;
+    }
+    if (entry.count >= limit) return false;
+    entry.count += 1;
+    return true;
+  };
+}
diff --git a/src/routes/notes.js b/src/routes/notes.js
index 8248dc1..9a2a3b9 100644
--- a/src/routes/notes.js
+++ b/src/routes/notes.js
@@ -1,8 +1,27 @@
 import { createNote, deleteNote, getNote, listNotes, updateNote } from '../services/notes.js';
 import { noteSummary } from '../utils/format.js';
+import { ValidationError } from '../utils/validate.js';
+
+const MAX_PAGE_SIZE = 50;
+
+function positiveInt(field, value, fallback) {
+  if (value === undefined) return fallback;
+  const n = Number(value);
+  if (!Number.isInteger(n) || n < 1) throw new ValidationError(field, 'must be a positive integer');
+  return n;
+}
+
+function listPage(req) {
+  const page = positiveInt('page', req.query?.page, 1);
+  const pageSize = Math.min(positiveInt('pageSize', req.query?.pageSize, 5), MAX_PAGE_SIZE);
+  const notes = listNotes(req.user.id);
+  const start = (page - 1) * pageSize;
+  const items = notes.slice(start, start + pageSize).map(noteSummary);
+  return { status: 200, body: { items, page, pageSize, total: notes.length } };
+}
 
 export const notesRoutes = {
-  'GET /notes': (req) => ({ status: 200, body: listNotes(req.user.id).map(noteSummary) }),
+  'GET /notes': listPage,
   'GET /notes/:id': (req) => {
     const note = getNote(req.user.id, req.params.id);
     return note ? { status: 200, body: note } : { status: 404, body: { error: 'not found' } };
diff --git a/src/utils/format.js b/src/utils/format.js
index 24a3a09..4c90f41 100644
--- a/src/utils/format.js
+++ b/src/utils/format.js
@@ -3,7 +3,7 @@
 // Dates are shown as YYYY-MM-DD in UTC.
 export function formatDate(ms) {
   const d = new Date(ms);
-  const month = String(d.getUTCMonth()).padStart(2, '0');
+  const month = String(d.getUTCMonth() + 1).padStart(2, '0');
   const day = String(d.getUTCDate()).padStart(2, '0');
   return `${d.getUTCFullYear()}-${month}-${day}`;
 }
diff --git a/tests/api.test.js b/tests/api.test.js
index 32d499e..519f328 100644
--- a/tests/api.test.js
+++ b/tests/api.test.js
@@ -18,8 +18,26 @@ test('notes need a valid token', () => {
 test('lists only my notes, newest first', () => {
   const res = as('u1', { method: 'GET', path: '/notes' });
   assert.equal(res.status, 200);
-  assert.equal(res.body.length, 8);
-  assert.equal(res.body[0].title, 'Car service');
+  assert.equal(res.body.total, 8);
+  assert.equal(res.body.items[0].title, 'Car service');
+});
+
+test('notes are paginated, default page size 5', () => {
+  const res = as('u1', { method: 'GET', path: '/notes' });
+  assert.equal(res.body.items.length, 5);
+  assert.equal(res.body.page, 1);
+  assert.equal(res.body.pageSize, 5);
+  const last = as('u1', { method: 'GET', path: '/notes', query: { page: '2' } });
+  assert.equal(last.body.items.length, 3);
+  assert.equal(as('u1', { method: 'GET', path: '/notes', query: { page: '3' } }).body.items.length, 0);
+});
+
+test('pageSize is capped at 50 and bad values are 400s', () => {
+  const big = as('u1', { method: 'GET', path: '/notes', query: { pageSize: '500' } });
+  assert.equal(big.body.pageSize, 50);
+  assert.equal(big.body.items.length, 8);
+  assert.equal(as('u1', { method: 'GET', path: '/notes', query: { page: '0' } }).status, 400);
+  assert.equal(as('u1', { method: 'GET', path: '/notes', query: { pageSize: 'abc' } }).status, 400);
 });
 
 test('creates and deletes a note', () => {
@@ -37,3 +55,9 @@ test('search ranks title matches first', () => {
   const res = as('u1', { method: 'GET', path: '/search', query: { q: 'list' } });
   assert.deepEqual(res.body.map((n) => n.title), ['Book list']);
 });
+
+test('formatDate uses 1-based months', async () => {
+  const { formatDate } = await import('../src/utils/format.js');
+  assert.equal(formatDate(Date.UTC(2026, 2, 15)), '2026-03-15');
+  assert.equal(formatDate(Date.UTC(2026, 11, 1)), '2026-12-01');
+});
diff --git a/tests/rateLimit.test.js b/tests/rateLimit.test.js
new file mode 100644
index 0000000..a6b1987
--- /dev/null
+++ b/tests/rateLimit.test.js
@@ -0,0 +1,55 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { createRateLimiter } from '../src/middleware/rateLimit.js';
+
+function setup(limit = 3, windowMs = 1000) {
+  const clock = { t: 0 };
+  const allow = createRateLimiter({ limit, windowMs, now: () => clock.t });
+  return { clock, allow };
+}
+
+test('allows up to limit calls per window, then blocks', () => {
+  const { allow } = setup();
+  assert.deepEqual([1, 2, 3, 4, 5].map(() => allow('a')), [true, true, true, false, false]);
+});
+
+test('keys are counted independently', () => {
+  const { allow } = setup(1);
+  assert.equal(allow('a'), true);
+  assert.equal(allow('a'), false);
+  assert.equal(allow('b'), true);
+});
+
+test('counter resets at the next multiple of windowMs', () => {
+  const { clock, allow } = setup(1);
+  clock.t = 999;
+  assert.equal(allow('a'), true);
+  assert.equal(allow('a'), false);
+  clock.t = 1000;
+  assert.equal(allow('a'), true);
+  assert.equal(allow('a'), false);
+});
+
+test('calls late in a window do not extend it', () => {
+  const { clock, allow } = setup(1);
+  clock.t = 1500;
+  assert.equal(allow('a'), true);
+  clock.t = 1999;
+  assert.equal(allow('a'), false);
+  clock.t = 2000;
+  assert.equal(allow('a'), true);
+});
+
+test('blocked calls do not carry into the next window', () => {
+  const { clock, allow } = setup(2);
+  for (let i = 0; i < 10; i++) allow('a');
+  clock.t = 1000;
+  assert.equal(allow('a'), true);
+  assert.equal(allow('a'), true);
+  assert.equal(allow('a'), false);
+});
+
+test('defaults to Date.now', () => {
+  const allow = createRateLimiter({ limit: 1, windowMs: 60 * 60 * 1000 });
+  assert.equal(typeof allow('a'), 'boolean');
+});