diff --git a/client/src/api/backup.ts b/client/src/api/backup.ts
new file mode 100644
index 0000000..7a285b4
--- /dev/null
+++ b/client/src/api/backup.ts
@@ -0,0 +1,9 @@
+import { api } from './client';
+
+export const EXPORT_BACKUP_URL = '/api/backup/export';
+
+export function importBackup(file: File) {
+  const formData = new FormData();
+  formData.append('backup', file);
+  return api.postForm<void>('/backup/import', formData);
+}
diff --git a/client/src/pages/AdminUsersPage.tsx b/client/src/pages/AdminUsersPage.tsx
index fc744a1..709c267 100644
--- a/client/src/pages/AdminUsersPage.tsx
+++ b/client/src/pages/AdminUsersPage.tsx
@@ -1,12 +1,15 @@
-import { useState, type FormEvent } from 'react';
+import { useState, type ChangeEvent, type FormEvent } from 'react';
 import { useUsers, useCreateUser, useUpdateUser, useResetPassword } from '../hooks/useUsers';
+import { useAuth } from '../context/AuthContext';
 import { ApiError } from '../api/client';
+import * as backupApi from '../api/backup';
 
 export function AdminUsersPage() {
   const { data: users, isLoading } = useUsers();
   const createUser = useCreateUser();
   const updateUser = useUpdateUser();
   const resetPassword = useResetPassword();
+  const { logout } = useAuth();
 
   const [username, setUsername] = useState('');
   const [password, setPassword] = useState('');
@@ -14,6 +17,7 @@ export function AdminUsersPage() {
   const [isAdmin, setIsAdmin] = useState(false);
   const [error, setError] = useState<string | null>(null);
   const [submitting, setSubmitting] = useState(false);
+  const [importing, setImporting] = useState(false);
 
   async function handleCreate(e: FormEvent) {
     e.preventDefault();
@@ -86,6 +90,32 @@ export function AdminUsersPage() {
     }
   }
 
+  async function handleImportFile(e: ChangeEvent<HTMLInputElement>) {
+    const file = e.target.files?.[0];
+    e.target.value = '';
+    if (!file) return;
+
+    if (
+      !window.confirm(
+        'Importing a backup permanently replaces all cities, users, and photos with the ' +
+          'contents of this file. This cannot be undone. Continue?',
+      )
+    ) {
+      return;
+    }
+
+    setImporting(true);
+    try {
+      await backupApi.importBackup(file);
+      window.alert('Import complete. You will now be logged out — please log back in.');
+      await logout();
+    } catch {
+      window.alert('Could not import backup. Make sure the file is a CityTracker backup zip.');
+    } finally {
+      setImporting(false);
+    }
+  }
+
   return (
     <div className="admin-users-page">
       <h1>Users</h1>
@@ -183,6 +213,29 @@ export function AdminUsersPage() {
           {submitting ? 'Creating…' : 'Create user'}
         </button>
       </form>
+
+      <section className="backup-section">
+        <h2>Backup</h2>
+        <p className="backup-hint">
+          Export all cities, users, and photos as a zip file. Importing a backup permanently
+          replaces all existing data.
+        </p>
+        <div className="backup-actions">
+          <a className="btn" href={backupApi.EXPORT_BACKUP_URL} download>
+            Export backup
+          </a>
+          <label className={`btn btn-danger ${importing ? 'btn-disabled' : ''}`}>
+            {importing ? 'Importing…' : 'Import backup'}
+            <input
+              type="file"
+              accept=".zip"
+              hidden
+              disabled={importing}
+              onChange={handleImportFile}
+            />
+          </label>
+        </div>
+      </section>
     </div>
   );
 }
diff --git a/client/src/styles/global.css b/client/src/styles/global.css
index 983815c..6c6ed1e 100644
--- a/client/src/styles/global.css
+++ b/client/src/styles/global.css
@@ -701,3 +701,37 @@ a {
   border: 1px solid var(--color-border);
   background: var(--color-bg);
 }
+
+/* Backup */
+
+.backup-section {
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius);
+  padding: var(--spacing-4);
+  max-width: 480px;
+}
+
+.backup-section h2 {
+  margin-top: 0;
+}
+
+.backup-hint {
+  color: var(--color-text-muted);
+  font-size: 0.9rem;
+}
+
+.backup-actions {
+  display: flex;
+  gap: var(--spacing-2);
+  flex-wrap: wrap;
+}
+
+.backup-actions a.btn {
+  text-decoration: none;
+}
+
+.btn-disabled {
+  opacity: 0.6;
+  cursor: not-allowed;
+}
diff --git a/package-lock.json b/package-lock.json
index e9e675c..67cd77e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2049,6 +2049,14 @@
         "acorn": "^6.0.0 || ^7.0.0 || ^8.0.0"
       }
     },
+    "node_modules/adm-zip": {
+      "version": "0.6.0",
+      "resolved": "https://registry.npmjs.org/adm-zip/-/adm-zip-0.6.0.tgz",
+      "integrity": "sha512-XleryMhbuksdKtofnWZ9Sk+4CUTbms4Mb/EU32SZwToAyZ5RgVos/ki8n+yr0LWHOGKuakbXTuuYNHLQjhddgg==",
+      "engines": {
+        "node": ">=14.0"
+      }
+    },
     "node_modules/ajv": {
       "version": "6.15.0",
       "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.15.0.tgz",
@@ -6360,6 +6368,7 @@
       "version": "1.0.0",
       "dependencies": {
         "@citytracker/shared": "*",
+        "adm-zip": "^0.6.0",
         "argon2": "^0.40.3",
         "better-sqlite3": "^11.3.0",
         "express": "^4.21.0",
diff --git a/server/package.json b/server/package.json
index 1763d14..03daf1c 100644
--- a/server/package.json
+++ b/server/package.json
@@ -11,6 +11,7 @@
   },
   "dependencies": {
     "@citytracker/shared": "*",
+    "adm-zip": "^0.6.0",
     "argon2": "^0.40.3",
     "better-sqlite3": "^11.3.0",
     "express": "^4.21.0",
diff --git a/server/src/app.ts b/server/src/app.ts
index cfb3127..de19412 100644
--- a/server/src/app.ts
+++ b/server/src/app.ts
@@ -6,6 +6,7 @@ import { authRouter } from './routes/auth.routes';
 import { usersRouter } from './routes/users.routes';
 import { citiesRouter } from './routes/cities.routes';
 import { geocodeRouter } from './routes/geocode.routes';
+import { backupRouter } from './routes/backup.routes';
 import { config } from './config';
 
 export function createApp() {
@@ -18,6 +19,7 @@ export function createApp() {
   app.use('/api/users', usersRouter);
   app.use('/api/cities', citiesRouter);
   app.use('/api/geocode', geocodeRouter);
+  app.use('/api/backup', backupRouter);
 
   app.use('/uploads', express.static(config.uploadDir));
 
diff --git a/server/src/routes/backup.routes.ts b/server/src/routes/backup.routes.ts
new file mode 100644
index 0000000..6392e88
--- /dev/null
+++ b/server/src/routes/backup.routes.ts
@@ -0,0 +1,41 @@
+import { Router } from 'express';
+import multer from 'multer';
+import { requireAuth } from '../middleware/requireAuth';
+import { requireAdmin } from '../middleware/requireAdmin';
+import * as backupService from '../services/backup.service';
+
+export const backupRouter = Router();
+
+backupRouter.use(requireAuth, requireAdmin);
+
+const backupUpload = multer({
+  storage: multer.memoryStorage(),
+  limits: { fileSize: 500 * 1024 * 1024 },
+});
+
+backupRouter.get('/export', (_req, res) => {
+  const zipBuffer = backupService.exportBackup();
+  const filename = `citytracker-backup-${new Date().toISOString().slice(0, 10)}.zip`;
+  res.setHeader('Content-Type', 'application/zip');
+  res.setHeader('Content-Disposition', `attachment; filename="${filename}"`);
+  res.send(zipBuffer);
+});
+
+backupRouter.post('/import', backupUpload.single('backup'), (req, res) => {
+  if (!req.file) {
+    res.status(400).json({ error: 'missing_file' });
+    return;
+  }
+
+  try {
+    backupService.importBackup(req.file.buffer);
+  } catch (err) {
+    if (err instanceof backupService.InvalidBackupError) {
+      res.status(400).json({ error: 'invalid_backup', message: err.message });
+      return;
+    }
+    throw err;
+  }
+
+  res.status(204).end();
+});
diff --git a/server/src/services/backup.service.ts b/server/src/services/backup.service.ts
new file mode 100644
index 0000000..fc35242
--- /dev/null
+++ b/server/src/services/backup.service.ts
@@ -0,0 +1,177 @@
+import fs from 'node:fs';
+import path from 'node:path';
+import AdmZip from 'adm-zip';
+import { db } from '../db/connection';
+import { config } from '../config';
+
+const BACKUP_VERSION = 1;
+const UPLOADS_ENTRY_PREFIX = 'uploads/';
+const DATA_ENTRY_NAME = 'data.json';
+
+interface UserRow {
+  id: number;
+  username: string;
+  password_hash: string;
+  is_admin: number;
+  is_active: number;
+  display_name: string | null;
+  created_at: string;
+}
+
+interface CityRow {
+  id: number;
+  name: string;
+  country: string;
+  country_code: string | null;
+  lat: number;
+  lng: number;
+  status: string;
+  visit_date_start: string | null;
+  visit_date_end: string | null;
+  notes: string;
+  liked: number;
+  photo_filename: string | null;
+  created_by: number;
+  created_at: string;
+  updated_at: string;
+}
+
+interface LinkRow {
+  id: number;
+  city_id: number;
+  url: string;
+  label: string;
+  position: number;
+}
+
+interface ParticipantRow {
+  city_id: number;
+  user_id: number;
+}
+
+interface BackupData {
+  version: number;
+  exportedAt: string;
+  users: UserRow[];
+  cities: CityRow[];
+  cityLinks: LinkRow[];
+  cityParticipants: ParticipantRow[];
+}
+
+export class InvalidBackupError extends Error {}
+
+export function exportBackup(): Buffer {
+  const data: BackupData = {
+    version: BACKUP_VERSION,
+    exportedAt: new Date().toISOString(),
+    users: db.prepare('SELECT * FROM users').all() as UserRow[],
+    cities: db.prepare('SELECT * FROM cities').all() as CityRow[],
+    cityLinks: db.prepare('SELECT * FROM city_links').all() as LinkRow[],
+    cityParticipants: db.prepare('SELECT * FROM city_participants').all() as ParticipantRow[],
+  };
+
+  const zip = new AdmZip();
+  zip.addFile(DATA_ENTRY_NAME, Buffer.from(JSON.stringify(data, null, 2)));
+
+  if (fs.existsSync(config.uploadDir)) {
+    for (const filename of fs.readdirSync(config.uploadDir)) {
+      const filePath = path.join(config.uploadDir, filename);
+      if (fs.statSync(filePath).isFile()) {
+        zip.addLocalFile(filePath, 'uploads');
+      }
+    }
+  }
+
+  return zip.toBuffer();
+}
+
+function parseBackup(buffer: Buffer): { data: BackupData; zip: AdmZip } {
+  let zip: AdmZip;
+  try {
+    zip = new AdmZip(buffer);
+  } catch {
+    throw new InvalidBackupError('The file is not a valid zip archive.');
+  }
+
+  const entry = zip.getEntry(DATA_ENTRY_NAME);
+  if (!entry) {
+    throw new InvalidBackupError('The zip is missing data.json — this is not a CityTracker backup.');
+  }
+
+  let data: BackupData;
+  try {
+    data = JSON.parse(zip.readAsText(entry));
+  } catch {
+    throw new InvalidBackupError('data.json is not valid JSON.');
+  }
+
+  if (
+    !data ||
+    !Array.isArray(data.users) ||
+    !Array.isArray(data.cities) ||
+    !Array.isArray(data.cityLinks) ||
+    !Array.isArray(data.cityParticipants)
+  ) {
+    throw new InvalidBackupError('data.json is missing expected fields.');
+  }
+
+  return { data, zip };
+}
+
+export function importBackup(buffer: Buffer): void {
+  const { data, zip } = parseBackup(buffer);
+
+  const runImport = db.transaction(() => {
+    db.prepare('DELETE FROM city_participants').run();
+    db.prepare('DELETE FROM city_links').run();
+    db.prepare('DELETE FROM cities').run();
+    db.prepare('DELETE FROM users').run();
+    db.prepare('DELETE FROM sessions').run();
+
+    const insertUser = db.prepare(
+      `INSERT INTO users (id, username, password_hash, is_admin, is_active, display_name, created_at)
+       VALUES (@id, @username, @password_hash, @is_admin, @is_active, @display_name, @created_at)`,
+    );
+    for (const row of data.users) insertUser.run(row);
+
+    const insertCity = db.prepare(
+      `INSERT INTO cities
+        (id, name, country, country_code, lat, lng, status, visit_date_start, visit_date_end,
+         notes, liked, photo_filename, created_by, created_at, updated_at)
+       VALUES
+        (@id, @name, @country, @country_code, @lat, @lng, @status, @visit_date_start, @visit_date_end,
+         @notes, @liked, @photo_filename, @created_by, @created_at, @updated_at)`,
+    );
+    for (const row of data.cities) insertCity.run(row);
+
+    const insertLink = db.prepare(
+      `INSERT INTO city_links (id, city_id, url, label, position)
+       VALUES (@id, @city_id, @url, @label, @position)`,
+    );
+    for (const row of data.cityLinks) insertLink.run(row);
+
+    const insertParticipant = db.prepare(
+      'INSERT INTO city_participants (city_id, user_id) VALUES (@city_id, @user_id)',
+    );
+    for (const row of data.cityParticipants) insertParticipant.run(row);
+  });
+
+  try {
+    runImport();
+  } catch (err) {
+    throw new InvalidBackupError(
+      `Could not import backup — the data is inconsistent (${(err as Error).message}).`,
+    );
+  }
+
+  fs.mkdirSync(config.uploadDir, { recursive: true });
+  for (const filename of fs.readdirSync(config.uploadDir)) {
+    fs.unlinkSync(path.join(config.uploadDir, filename));
+  }
+  for (const zipEntry of zip.getEntries()) {
+    if (zipEntry.isDirectory || !zipEntry.entryName.startsWith(UPLOADS_ENTRY_PREFIX)) continue;
+    const filename = zipEntry.entryName.slice(UPLOADS_ENTRY_PREFIX.length);
+    if (!filename || filename !== path.basename(filename)) continue;
+    fs.writeFileSync(path.join(config.uploadDir, filename), zipEntry.getData());
+  }
+}