What does end-to-end encryption mean here?
The sending device derives a key from your room code locally, then encrypts text, filenames, and file contents before transmission. A receiving device with the same code decrypts them in its own browser. The server handles ciphertext rather than the original content.
How the room code works
The room code both brings devices into the same room and provides the basis for deriving the local encryption key. The code itself is never sent to the server. Security depends on using a unique, hard-to-guess code rather than a name, birthday, sequence, or other public information.
How temporary files are handled
An encrypted file is stored only for short-term handoff and expires after 30 minutes by default. During download, the browser retrieves ciphertext, decrypts it locally, and creates the file you save. Confirm that the receiving device has finished before closing the room.
Security boundaries to remember
End-to-end encryption cannot protect a device already controlled by malware, and anyone who obtains the room code may enter the room. Use a trusted, updated browser, share room links through a safe channel, and avoid exposing codes on public screens.