# STUN and TURN servers

Calls connect peers directly. STUN helps each side discover its public address; TURN relays the
media when a direct path is blocked (strict firewalls, symmetric NAT, some mobile networks).

## Defaults

Quibble ships working defaults so calls just work with no setup:

- **STUN:** Cloudflare (`stun:stun.cloudflare.com:3478`) - free, no account.
- **TURN:** Metered's shared open relay - free, no account.

The default TURN is shared by every Quibble user and is rate-limited. It is fine for trying things
out, but for reliable calls under strict networks, use your own.

## Which servers need an API key?

STUN is usually keyless. TURN almost always needs credentials, because relaying traffic costs
bandwidth. Common providers:

| Provider | Needs key? | Notes |
|----------|-----------|-------|
| Metered (shipped default) | No (shared key baked in) | Rate-limited, shared by everyone |
| Metered (your own) | Yes | Free tier; sign up for a username + credential |
| Twilio | Yes | Pay per GB |
| Cloudflare Realtime TURN | Yes | Requires a token |
| Self-hosted coturn | You set it | Full control, no third party |

## Use your own server

Open **Settings → STUN/TURN** and fill in:

- **TURN Server** - e.g. `turn:your.host:3478`
- **Username** and **Password / API key** - from your provider

Your TURN server then replaces the shared default. Settings are stored locally on your device.

To set a default for every client a server hands out, start the server with `TURN_URL`,
`TURN_USERNAME`, and `TURN_CREDENTIAL` (or a full `QUIBBLE_ICE_SERVERS_JSON` list). See
[server.md](server.md).