About ZCHAT
ZCHAT is a privacy-first encrypted messenger for Android. Your identity is a Zcash address, so there is no phone number, no email, and no account to register. Every message is end-to-end encrypted on your device, and each conversation chooses how that message travels: as a memo inside a Zcash shielded transaction, or free over NOSTR relays. See the three transport modes.
ZCHAT won the Zcash track at the first Zypherpunk Hackathon in December 2025 and has been in continuous development since. It is a one-person project, self-funded, with no grant funding to date. Both repositories are MIT-licensed and public. No third-party security audit has been done yet; one is targeted for Q4 2026.
Demo Video
Core Protocol Features
Conversation ID-based threading
End-to-end encrypted: ECDH P-256, HKDF, AES-256-GCM
Shielded on-chain, Tunnel, or Open, chosen per conversation
Split large messages across multiple memos
Save, nickname, and organize contacts
Safety numbers and key-change alerts (trust on first use)
Persistent chat history with threading
Send payments with messages
Optional delivery confirmations
React to messages with emoji
Quote and reply to specific messages
Set availability status
Request ZEC from contacts
Schedule, block-height, and conditional reveals
App Features
End-to-end encrypted WebRTC, DTLS-SRTP. Our TURN server relays media and sees call metadata
Encrypted attachments, images, and voice messages
Per-conversation expiry timers
In-app swap into ZEC through a third-party provider
Opt-in wipe triggered by a secret phrase you choose
Opt-in and separate from messaging; prompt text reaches a third-party provider in plaintext
Group Messaging
Group messaging specification
Create named groups with members
Invite users to join groups
AES-256-GCM encrypted group chat
Exit groups with notification
View members and group info
Rotate the group key when members leave
Signed admin actions: promote admins, remove members
Hand a group over to another admin
Roadmap
Publish the security-hardening branch and cut a release so public source, published APK, and audited tree are one artifact. Targeted end of Q3 2026
None has been done to date. Targeted for Q4 2026, followed by remediation and a 90-day disclosure window
Today the ratchet keeps a persistent root. A full double ratchet is designed but not shipped
Not started, no Swift code yet. Begins after audit remediation; no date promised
After audit remediation. Nothing has been submitted to any store yet
Only the lightwalletd server is user-configurable today
Full protocol specification available in the source code repository. Android only, with no iOS and no web client today. Distribution is a direct signed APK from GitHub Releases; ZCHAT is not in any app store yet, and there is no waitlist or invite gate. Latest published release: v2.12.4 (12 July 2026).