Privacy by Architecture.
Open-source, zero-knowledge sync for calendars, contacts, and tasks. Plaintext stays off the server; keys stay on-device.
⭐ Star this repo to help early testers find SilentSuite · Create your account · Self-host · Android APK · Help test
SilentSuite is an end-to-end encrypted alternative to Google Calendar, iCloud, and other cloud sync services. Events, contacts, and tasks are encrypted before they reach the sync server.
- 📅 Calendar: encrypted events and reminders
- 👥 Contacts: encrypted address book sync
- ✅ Tasks: encrypted to-do lists
- 🔌 Bridge: local CalDAV/CardDAV for apps like Apple Calendar and Thunderbird
- 🤖 Android: signed APK syncs into Android calendar, contacts, and task providers
- 🍎 iOS: the open-source EteSync app works with the same protocol while a native app is not ready yet
Built on the open Etebase protocol. Open source, self-hostable, EU-hosted for the managed service, GDPR-baseline.
Most calendar and contact sync services can read the data they store. SilentSuite is built for people who want sync without handing over plaintext.
- Zero-knowledge by default: encryption is always on, with no opt-out mode
- Open and auditable: server, web app, bridge, and Android code are open source
- No lock-in: export your data, use standard clients through the bridge, or self-host
- No private-data monetisation: paid hosting funds development; sync contents are unreadable to us
- Practical beta: usable today, but still honest about what is not ready yet
| Status | Details |
|---|---|
| Available now | Hosted web app, self-hosting, Android APK, CalDAV/CardDAV bridge, calendar/contact import-export, task export |
| In progress | F-Droid and Google Play listings, broader Android testing, DAV client compatibility reports |
| Not in this beta | Native iOS app, push notifications, shared calendars/contacts, OAuth Google/iCloud import |
Your device encrypts and decrypts locally. The sync server stores ciphertext and never receives your encryption keys. The CalDAV/CardDAV bridge only exposes plaintext on localhost, then syncs encrypted data upstream.
Hosted-service metadata is still visible where needed to operate the service: account and billing details, approximate encrypted storage size, sync timing, IP-level network logs, and operational metadata. Event titles, contact fields, task contents, notes, descriptions, locations, and reminders stay encrypted.
Crypto: XChaCha20-Poly1305, Argon2id, libsodium, and the open Etebase protocol.
Create an account at app.silentsuite.io/signup. Start with 7 days free without a card, or 30 days with a card; plans from €3/mo after trial.
Install the signed APK from GitHub Releases, or add this repo to Obtainium for update notifications.
git clone https://github.com/silent-suite/silentsuite.git
cd silentsuite/self-host
cp .env.example .env # then edit
docker compose up -dFull setup guide: Self-Hosting.
Useful feedback right now:
- Android APK testing across device models and Android versions
- Bridge compatibility reports for Thunderbird, Apple Calendar, Evolution, GNOME Calendar, and other DAV clients
- Self-hosting verification on fresh servers
- Web app translation proposals and review from fluent human translators
- Docs and trust review for vague privacy claims or confusing setup steps
Open a GitHub issue with logs/screenshots where useful. Do not paste secrets, passwords, or private calendar/contact data.
Want a small first PR? See the open good first issues.
Security issues: email info@silentsuite.io rather than opening a public issue.
Bug reports, feature requests, and PRs are welcome.
⭐ Star this repo to help early testers, contributors, and privacy users find the project.
Developer information
git clone https://github.com/silent-suite/silentsuite.git
cd silentsuite
pnpm install
pnpm devThe Etebase sync server, CalDAV/CardDAV bridge, and Android adapter each have their own setup. See the Contributing guide for the full dev environment.
| Component | Technology |
|---|---|
| Sync server | Python, Etebase protocol, Django |
| Web app | Next.js 15, React, Tailwind CSS |
| Docs site | VitePress, Vue, Cloudflare Workers |
| CalDAV/CardDAV bridge | Python, Radicale |
| Android adapter | Kotlin |
| Encryption | Etebase protocol, XChaCha20-Poly1305, Argon2id, libsodium |
| Path | What it is |
|---|---|
apps/web/ |
Web app at app.silentsuite.io |
apps/docs/ |
Documentation site |
packages/ |
Shared TypeScript packages |
server/ |
Etebase sync server |
bridge/ |
CalDAV/CardDAV bridge |
android/ |
Android sync adapter |
self-host/ |
Docker self-hosting setup |
docs/ |
Markdown documentation |
The marketing site and billing/accounts API live in a separate private repo and have no cryptographic responsibilities.
AGPL-3.0 · android/LICENSE (GPL-3.0)