How your audio travels

Audio: browser to browser, encrypted

Calls use WebRTC, the standard built into every modern browser. Once the browsers have found each other, the audio flows straight between them, peer to peer. WebRTC always encrypts media (DTLS-SRTP); the keys are negotiated by the two browsers and are never known to us.

One exception: when a strict firewall blocks every direct path, the audio can be forwarded by a relay (Cloudflare's TURN service). The relay only passes on encrypted packets it cannot decrypt, and it is used only when a direct connection is impossible.

What our server handles

• The session itself: its code, the show title, when the link expires, and the email address of the person who opened it. The email address is never shown to guests.
• The connection setup messages the browsers exchange to find each other, including the network addresses they can be reached on, and the guest's name and location, which are shown to the studio.

All of it lives only as long as the session. When the studio ends the session or the link expires, it is deleted.

Spam protection

Opening a session needs a valid email address and passes Cloudflare Turnstile, which checks that a person rather than a bot is behind the request. Turnstile runs only on the start page, under Cloudflare's privacy policy. Guests are not asked to do either.

Recordings

The recorder runs in the studio's browser tab. Recordings are made and saved on the studio's computer and are never uploaded.

What we log

Only anonymous session usage: when a session is created and ended, how long it was valid and lasted, and how many guests took part. No names, email addresses, show titles, locations, IP addresses or audio. We set no cookies and use no analytics or trackers. Your device choices (microphone, output, your name and email for next time) are remembered in your own browser only.

callin. runs on Cloudflare. As our hosting and network provider, Cloudflare processes the connections to the site under its own privacy policy.