An encrypted messenger, all the way through.

“Encrypted” is on almost every messenger's website, and it can mean very different things. Sometimes it only means the connection to the company's server is protected, while the company can still read everything it stores. Sometimes end-to-end encryption exists but has to be switched on per chat, or doesn't cover groups. Frozen Chat is an end-to-end encrypted messenger in the strict sense: content is locked on your phone before it leaves, and only the people in the conversation hold the keys. If you are new to the idea, start with what is end-to-end encryption?

What is encrypted

The Signal protocol, with post-quantum keys

One-to-one chats use libsignal, the library behind the Signal app, without changes. Each conversation begins with PQXDH, which combines classic elliptic-curve key agreement with ML-KEM (Kyber), a post-quantum algorithm standardised by NIST. That protects against “harvest now, decrypt later”, where someone records encrypted traffic today and waits for a quantum computer. Our explainer post-quantum encryption in messaging covers this in plain language.

After the handshake, the Double Ratchet gives every message its own key. One stolen key doesn't unlock earlier messages (forward secrecy), and the conversation heals itself after a compromise (post-compromise security).

Groups on MLS, the IETF standard

Groups use Messaging Layer Security, published by the IETF as RFC 9420, with a hybrid post-quantum cipher suite. The server orders encrypted group messages but is never a member and never holds group keys. It also can't slip a device into a group: every app checks each member against that person's signed device list. When someone leaves or is removed, the group moves to new keys.

Encryption is only half of privacy

Even with perfect encryption, a server can learn a lot from metadata: who talks to whom, when, and from where. Frozen Chat is designed to keep that small.

• No phone number, no e-mail. Accounts are usernames, looked up by keyed hash. See messenger without a phone number.
• Sealed sender. The server delivers messages without being told who sent them.
• No logs. No access logs and no IP addresses are kept. Stored timestamps are rounded.
• Empty notifications. Pushes through Google or Apple carry no message, no sender and no chat, just “wake up”.
• No trackers. No analytics in the app or on this website.

Keys that stay with you

Your private keys are generated on your phone and stored in an encrypted database protected by the phone's secure hardware where available. When you create an account you get a 24-word Recovery Key, shown once, on your device only. You can verify each contact with a safety number and the app warns you if a contact's keys change.

Honest about the limits

No messenger is magic. The first contact with someone is trust-on-first-use until key transparency is added, so compare safety numbers with people who matter. The web app is lower assurance than the phone app, because a browser runs whatever code the server sends. A phone that is unlocked and compromised can read what that phone can read. All of this is documented on the security page.

More than encrypted text

Frozen Chat is a full messenger: voice and video calls, voice messages, one-time photos and videos, stickers bundled with the app, app lock, multi-device with a web app, and self-destructing private notes you can send to anyone as a link. Make it look the way you like with themes. Wondering how it stacks up? Compare it with Signal, WhatsApp or Telegram.