Privacy Policy¶
Last updated: January 2, 2026
Overview¶
Mycel is a decentralized, peer-to-peer messaging application. This privacy policy explains what data Mycel collects, how it's used, and your rights.
The short version: Mycel collects no personal data. Messages are end-to-end encrypted. There are no servers storing your information.
Data We Collect¶
Data We DON'T Collect¶
- Personal information (name, email, phone number)
- Location data
- Usage analytics
- Message content
- Contact lists
- Device identifiers sent to any server
Data Stored on Your Device¶
Mycel stores the following locally on your device only:
| Data | Purpose |
|---|---|
| Cryptographic keys | Your identity (never leaves device) |
| Messages | Your conversations (encrypted) |
| Contacts | People you communicate with |
| Routing tables | For message delivery optimization |
This data is stored in a local database and is not transmitted to any server.
How Messages Work¶
Peer-to-Peer Relay¶
Messages travel through other Mycel users' devices to reach their destination. When relaying:
- Other devices temporarily store your encrypted message
- They cannot decrypt or read the content
- They can see destination identifiers (to route the message)
- Messages are deleted after delivery or expiration
End-to-End Encryption¶
All messages are encrypted on your device before transmission. Only the intended recipient can decrypt them. Not even relay devices can read your messages.
Third-Party Services¶
Nostr (Optional)¶
If you enable Nostr transport:
- Messages are relayed through public Nostr servers
- These servers may log connection metadata
- Message content remains encrypted
- You can disable Nostr for maximum privacy
Google Nearby Connections¶
Mycel uses Google's Nearby Connections API for local device discovery. This API operates locally and does not send data to Google servers.
Your Rights¶
You can:
- Delete your data by uninstalling the app
- Disable Nostr for offline-only operation
- View stored data in the app's data directory
- Export your messages (feature planned)
Data Retention¶
- Messages are stored until delivered or expired (TTL)
- Local data persists until you uninstall the app
- No data is retained on any server (there are no servers)
Security¶
We implement:
- End-to-end encryption (X25519 + AES-GCM)
- Digital signatures (Ed25519)
- No central points of failure
- Open source code for transparency
Children's Privacy¶
Mycel is not directed at children under 13. We do not knowingly collect information from children.
Changes to This Policy¶
We may update this policy. Changes will be noted in the changelog and on this page.
Contact¶
For privacy concerns, open an issue on GitHub or contact the maintainers.
Mycel is open source software. This policy reflects our commitment to user privacy.