How it works
Everything is encrypted on your device. The server passes along data it can’t read, and forgets it soon after.
The link is the key
A room link looks like bchr.xyz/#/k3v9…. The part after # is the room’s secret, and browsers never send it to a server.
From it, your browser derives (PBKDF2, then HKDF) an anonymous room ID the server uses to route messages, and an AES-256-GCM key that never leaves your device. Every message and file is encrypted with that key before it’s sent.
What the server sees
Can’t see
What you write, file names or contents, room names, or which link a room belongs to.
Can see
Anonymous room IDs, message sizes and times, how many people are connected, and their IP addresses (in memory only).
The server also vouches for names: it marks who really sent each message, so nobody can pose as you.
What’s kept, and for how long
Rooms
Nothing after everyone leaves. Files are deleted soon after.
Rooms with shared history
Recent messages, encrypted, in memory, until the room has been empty for two minutes.
Forums
Encrypted posts and files for the days chosen (1 to 30), then deleted.
Direct messages
Encrypted for each of your devices, kept from an hour up to 30 days, as the sender picks.
Notifications
A notification carries the message still encrypted. Your phone decrypts it itself, so neither the server nor Apple’s or Google’s push services see the text.
The limits
Anyone with a room’s link can join, so share it only with the people you mean to. The server knows when and how much you send, just not what. Accounts are optional, and without one you appear under a random anon-1234 name.