Zero-knowledge private messaging
Say nothing to the server.
Zero Say is a messenger built around one rule: the server must never be able to say anything about you. No phone number, no contacts, no analytics, and keys that only exist on your devices.
iPhone, Android, macOS, Windows and Ubuntu. Same encryption everywhere.
Three zeros
Privacy that doesn’t depend on trusting us.
01
Zero knowledge
Keys are generated on your device and never leave it. The server relays sealed envelopes it cannot open, so there is nothing to read, leak or sell.
02
Zero identity
No phone number, no email, no contact upload. You are a random identifier and a key pair. Share a handle or a QR code, nothing more.
03
Zero trace
No analytics, no ads, no third-party SDKs, no cookies on this site. What the app collects fits in one short table, and we publish it.
How it works
Four steps, none of them ours.
Everything that matters happens on your device. The relay in the middle is deliberately dumb.
- 01
Keys on your device
Installing Zero Say creates your key pair locally. You get a recovery phrase; we get nothing.
- 02
Sealed end to end
Every message is encrypted for the recipient's devices before it leaves yours. Forward secrecy, per-message keys.
- 03
Metadata kept minimal
Envelopes carry only what routing needs. Delivered messages are deleted from the relay immediately; undelivered ones after 30 days.
- 04
Verify who you talk to
Compare safety numbers in person or by QR. If a key ever changes, both sides are told, loudly.
Download
Every platform. One promise.
iPhone & iPad
App Store
iOS 17
Android
Google Play
Android 10
macOS
Apple Silicon · .dmg
macOS 13 Ventura
macOS
Intel · .dmg
macOS 13 Ventura
Windows
x64 · .exe
Windows 10
Windows
ARM64 · .exe
Windows 11
Ubuntu / Debian
x86_64 .deb · .deb
Ubuntu 22.04
Ubuntu / Debian
ARM64 .deb · .deb
Ubuntu 22.04
Questions
Straight answers.
What does “zero knowledge” actually mean here?
Your messages are encrypted on your device with keys that only exist on your devices. The server relays sealed envelopes it cannot open. It never has the keys, so there is nothing it could hand over, leak or sell.
Do I need a phone number?
No. A Zero Say account is a random identifier plus a key pair generated on your device. You share a handle or a QR code, not your number, and we never ask for access to your contacts.
What does Zero Say know about me?
As little as an app can and still deliver messages: your account identifier, the push token your phone hands us, and the minimum routing data needed to move a message from one device to another. No profiles, no analytics, no advertising identifiers.
Can you read my messages if the police ask?
We cannot read them ourselves, so we cannot give them to anyone. We can only respond with what exists on our side, which is the short list above. We publish that list in the privacy policy and keep it short on purpose.
What happens if I lose my phone?
Your keys live on the device. Without your backup phrase the old messages are gone, and we cannot recover them. That is the trade: nobody can restore what nobody but you could read.
Is it free? Is the code open?
The app is free to use. The protocol and the clients will be published under an open licence before the first stable release so anyone can verify what the app does with your data.
Say less. Keep everything.
Install Zero Say, share your handle, and stop feeding a server that never needed to know.