OSChat

A one-to-one chat app with end-to-end encryption, for Android, iPhone and iPad. There is no account to create — you connect with someone by scanning their QR code or opening an invite link, and the app never asks for your name, phone number, email or contacts. Free, with no ads.

Messages, photos and files are encrypted on your phone and can only be opened on the other person's. Every message gets a fresh key (X25519 and the Double Ratchet), and a relay server run by us carries the ciphertext between you. It holds a message only until the other phone collects it — 30 days at most — and cannot read any of it.

After connecting, compare the safety number on both screens to make sure nobody sits in between. Your name and profile photo travel the same encrypted way, and the nicknames you give your contacts never leave your phone.

Notifications are built on the device after it has decrypted the message itself, so the push signal carries no content. On the lock screen you see who wrote, not what they wrote.

Nothing is backed up — not to Google, not to iCloud, not to us. That is the point, but it also means a lost phone takes its conversations with it.

Android and iOS talk to each other, and the interface comes in ten languages.

• No account, no phone number — connect by QR code or invite link
• Messages, photos and files end-to-end encrypted
• Safety numbers to check who you are talking to
• The relay server holds only ciphertext, and only until delivery
• No ads, no backups