Frequently Asked Questions

ZChat is an encrypted messenger where every message is a Zcash shielded transaction. Instead of routing messages through a centralized server, ZChat encodes them as encrypted memos inside Zcash shielded transactions. This means your messages inherit the privacy guarantees of the Zcash protocol — hidden sender, hidden receiver, hidden content.

Signal and WhatsApp encrypt message content, but their servers still see who is messaging whom, when, and how often (metadata). ZChat messages are Zcash shielded transactions, so on-chain metadata is hidden by the Zcash protocol. However, ZChat is early-stage beta software without a third-party audit, while Signal is battle-tested and recommended for most users.

No. Messages are encrypted memos inside Zcash shielded transactions. The ZChat backend infrastructure (zebrad, lightwalletd) handles blockchain synchronization only — it never sees your message content. Your messages live on the Zcash blockchain.

Zcash shielded transactions hide sender address, receiver address, and amount on-chain. The memo field (which contains your message) is also encrypted. However, network-level metadata (IP address when broadcasting transactions) is NOT hidden by ZChat — you would need to use Tor or a VPN for that. See our Security page for the full threat model.

Yes. The source code is available on GitHub at github.com/decentrathai/zchat (backend + landing) and github.com/decentrathai/zchat-android (Android app, forked from the official Zcash wallet Zashi). The license is GPLv3.

No. ZChat has not received a third-party security audit. It is experimental software in private beta. We strongly recommend not using it for high-stakes communications until an audit has been completed. The Zcash protocol itself has been audited, but ZChat’s application layer has not.

ZChat is currently in Android private beta. You can request early access on our download page. Once approved, you’ll receive a download code via email to download the APK directly.

No. ZChat does not require a phone number, email, or any personal information to create an account. Your identity is a Zcash shielded address derived from a BIP39 seed phrase.

The app is free. However, each message is a Zcash shielded transaction, which costs a small network fee (typically less than $0.01 USD). You need a small amount of ZEC to send messages.

Not yet. Android is the only platform currently supported. iOS and desktop versions are planned but have no release date.

ZMSG is ZChat’s message format protocol (currently v4). Each message is encoded as a pipe-delimited string inside a Zcash memo field: ZMSG|4|type|conv_id|sender_hash|payload. It supports message types including text, key exchange (KEX), reactions, receipts, replies, payment requests, status updates, and check-ins. See our Protocol page for the full specification.

ZChat uses two layers of encryption: (1) Zcash protocol encryption — shielded transactions encrypt the memo field containing your message, and (2) Application-layer E2E encryption using secp256r1 ECDH key exchange with AES-256-GCM, with keys derived via HKDF (RFC 5869). Group messages use ECIES for per-recipient key encryption.

Zcash shielded transaction memos are limited to 512 bytes. ZChat uses the ZMSG v4c chunking protocol to split longer messages across multiple transactions, which are reassembled by the recipient.

Not yet. File and image sharing is planned via NOSTR/Blossom protocol integration, but is not currently available.

You lose access to your identity and message history. There is no recovery mechanism. Back up your seed phrase securely.

For most people, Signal is the better choice — it’s mature, audited, and widely used. ZChat is best for users who specifically want message transport via Zcash shielded transactions and are comfortable with beta software. See our Comparison page for a detailed breakdown.

Session routes messages through a decentralized onion network (Lokinet). ZChat stores messages as Zcash shielded transactions on the blockchain. Session has been audited and is more mature. ZChat offers tighter integration with Zcash payments. Both avoid phone number requirements.

Partially. Messages are stored on the decentralized Zcash blockchain, but the current beta relies on ZChat’s backend infrastructure for blockchain synchronization and lightwalletd access. Users cannot yet run fully independent nodes, though the architecture supports it.

ZChat was built for the Zypherpunk Hackathon 2025 and received a prize in the Zcash-related projects track. Development continues as an open-source project. The source code is on GitHub.

Email [email protected] or report via GitHub at github.com/decentrathai/zchat/security. See our security.txt at zsend.xyz/.well-known/security.txt.