A privacy-focused, offline-capable todo app with end-to-end encrypted sync across devices. No accounts, no tracking, no ads.

Live: todo.73.nu

• Single, range, and recurring todos (daily, weekly, biweekly, monthly, yearly, with span mode for flexible windows, e.g. Friday to Sunday)
• Tags with built-in presets (Urgent, Reminder, Low priority) and custom tags. Filter the day view by one or more tags at once, including across isolated folders
• Folders with colors, per-device hide/isolate options, and the ability to exclude folders from sync
• Drag & drop reordering for mouse and touch
• End-to-end encrypted sync using AES-256-GCM, key derived with PBKDF2 (100,000 iterations). The server never sees your data
• Shared folders to share individual folders with others via a separate sync key
• Offline-first PWA that is installable, works without internet, and syncs when back online
• Bilingual base-support for English and German
• Dark/light theme with customizable accent color
• Import/export as JSON
• Clean Up tool to remove past todos and trim old completion history
• GDPR-friendly with no analytics, no cookies, no user accounts
• Community translations via a built-in translation editor. Contributors are credited by name with an optional link

Sync is opt-in. When enabled:

1. Your todos are encrypted locally with AES-256-GCM before leaving your device
2. The encryption key is derived from your sync key using PBKDF2
3. Only the encrypted blob is sent to the server, never the key
4. A SHA-256 hash of your sync key is used as the server-side identifier
5. Conflict resolution merges completion dates from both sides and uses _modified timestamps for content conflicts. Schedule fields (date, recurrence, etc.) participate fully in conflict detection

Anyone with your sync key has full access to the encrypted data. Treat it like a password.

The app is a static frontend. You can host it on any web server, CDN, or even open index.html directly in a browser. PHP is only required if you want to use the sync feature.

1. Clone the repository
2. Serve the files from any static host (Nginx, Apache, GitHub Pages, Netlify, etc.)
3. Done. No server-side setup needed

All data is stored in localStorage on the device.

• PHP 8.0+ with file write access
• A writable directory for sync_data/

1. Clone the repository
2. Point your web server at the project root
3. Ensure sync.php and the directory it lives in are writable by the web server process
4. No database or configuration file needed

sync_data/ is created automatically on first use.

These can be adjusted inside sync.php.

• sync_data/ should not be publicly browsable. Add a .htaccess deny rule or equivalent
• The sync endpoint does not require authentication beyond the write/delete tokens derived from your sync key
• Disabling sync in the app does not delete server data. Use the "Delete Server Data" button in Settings to remove it

The app uses a service worker (sw.js) for offline capability and fast repeat loads.

On install, the following files are precached with cache: 'reload' to always fetch fresh copies: /, /index.html, /style.css, /script.js, /qr.js, /lz.js, /site.webmanifest

On activate, all caches from previous versions are deleted. The cache is versioned (CACHE_NAME = 'v1'), so bumping this string causes old caches to be purged on the next visit.

Fetch strategy:

• sync.php requests bypass the service worker entirely, so sync always goes directly to the network
• Navigation requests (loading the app) try the network first, fall back to cached index.html if offline, and update the cache on success
• All other static assets use stale-while-revalidate: the cached version is served immediately for speed, while a background fetch updates the cache for next time. If there is no cache yet, it waits for the network

This means the app loads instantly on repeat visits and remains fully functional without an internet connection. Sync resumes automatically once the device is back online.

When self-hosting: if you add or rename static files, update PRECACHE_URLS in sw.js and increment CACHE_NAME to ensure all clients pick up the new cache on their next visit.

Language files live in /i18n/ as separate .js files loaded and cached on demand. English and German are built-in, community translations are managed through a translation editor.

• Anyone can pick a language, translate keys, save a draft link, and submit for review
• Submissions go to a pending queue. The admin reviews a diff of changed keys before approving
• Approved translations are published as a new .js file and appear in the app's language selector
• Contributors are credited by name (with optional URL) in the app when their language is active

/
├── index.html          # App shell
├── script.js           # All app logic (Store, Sync, UI)
├── style.css           # Styles
├── sync.php            # Sync backend
├── sw.js               # Service worker
├── qr.js               # QR code generator
├── lz.js               # LZ-Compression library
├── site.webmanifest    # PWA manifest
└── i18n/               # Translations
    ├── en.js           # English (built-in)
    ├── de.js           # German (built-in)
    ├── langs.json      # Language registry

MIT, see LICENSE

Built by Christian Leroch · Support this project