ZK Privacy Policy
Summary
ZK is built so that we never have access to your message content, your contact list, or your real identity. What we don't have, we can't sell, leak, or hand over.
What we don't collect
- No phone number, email, or real name is needed to create an account.
- Message content is end-to-end encrypted (X3DH + Double Ratchet); keys exist only on your and your contact's devices.
- Contacts and chat history are stored only on your device, encrypted.
- The app contains no analytics, advertising, or tracking SDKs.
What is unavoidably visible
- Relays and offline mailboxes forward encrypted packets when a direct connection is impossible, and hold them for up to 72 hours for offline contacts. They see your IP address, your public key identifier (PeerID), and packet timing and size, never message content. Relay logs are kept for at most 72 hours.
- Direct connections: your contact sees your IP address.
- DNS: the app looks up bootstrap.zkim.app to find relays; your DNS provider sees that lookup.
- This website serves public downloads and release information. Our web hosts process requests and IP addresses to deliver these files. The app fetches the same public release information to check for updates. The site sets no cookies and runs no analytics or trackers.
- Support email: mail to support@zkim.app is forwarded to the team's inbox and used only to reply.
QR scanning and camera
The camera is used only to scan a contact's QR code. Frames are processed on the device and never sent anywhere.
Backups
Backups are encrypted with a passphrase you choose (Argon2id + XChaCha20-Poly1305) and stored wherever you decide. We have no copy and cannot open a backup if you forget the passphrase.
Legal requests
We do not hold message content or keys, so we cannot hand them over. Transient relay data (IP and connection times) is kept for at most 72 hours.
Limits
ZK is not fully anonymous: a network observer can see that you use ZK. Encryption does not protect messages on a device that is compromised or unlocked in someone else's hands.