Client SDK

HTTP & WebSocket API

Lower-level P2P token minting and the signaling WebSocket protocol. Use @radist-tech/client to skip this and work at a higher level. Call creation requires a secret key — see the Server SDK API reference.

HTTP API

All endpoints live under /api/v1. All responses are JSON. These endpoints accept a rad_pk_... public key.

POST /api/v1/p2p/calls/:callId/token

Mints another participant token for an existing call. Authenticated with Authorization: Bearer rad_pk_....

TypeScript

const response = await fetch(
  `https://radist.tech/api/v1/p2p/calls/${callId}/token`,
  {
    method: 'POST',
    headers: {
      Authorization: 'Bearer <your public key>'
    }
  }
);

const { callToken } = await response.json();

Status	Response
200	{ "callToken": "ct_..." }
401	{ "error": "Missing bearer token." } or invalid public key
404	{ "error": "Call not found." }
409	{ "error": "All peers are already connected." }
410	{ "error": "Call has been terminated." }

WebSocket API

Custom clients connect to the signaling WebSocket with a public key and either a fresh call token or a full reconnect payload. The browser SDK manages this protocol automatically.

Initial connection

TypeScript

const ws = new WebSocket(
  'wss://radist.tech/api/v1/p2p/signaling/ws' +
    '?publicKey=<your public key>' +
    '&callToken=ct_abc123...'
);

Connection process

Validate that the public key belongs to a project.
Atomically consume the call token for that project.
Register the socket and join the caller as a peer in the call.
Return a peer ID, reconnect token, and current call snapshot.

Reconnect

Reconnect by opening a new socket with the public key, call ID, previous peer ID, and reconnect token. This is what connection.reconnect() wraps in the browser SDK.

TypeScript

const ws = new WebSocket(
  'wss://radist.tech/api/v1/p2p/signaling/ws' +
    '?publicKey=<your public key>' +
    '&callId=550e8400-e29b-41d4-a716-446655440000' +
    '&peerId=peer_a1b2c3' +
    '&reconnectToken=rt_abc123...'
);

Connection errors

Close / Code	Message
4400 invalid_connection_request	Provide either callToken or the full reconnect payload.
4401 unauthorized	Invalid public key.
4401 invalid_token	Invalid or already consumed call token.

Client → server messages

Type	Fields	Description
signal	targetPeerId, signalType, payload?	Forward SDP offers, SDP answers, or ICE candidates to a connected peer.
leave	requestId?	Gracefully leave the current call.

Server → client messages

Type	Fields	Description
call_joined	callId, peerId, reconnectToken, call	The socket joined a call with a new peer identity.
call_reconnected	callId, peerId, call	The socket reconnected with a previous peer identity.
peer_joined \| peer_reconnected \| peer_left	callId, peerId, reason?, call	Lifecycle updates for the other peer in the call.
call_left	callId, peerId, reason, call	Confirmation that the current socket left or disconnected.
signal	callId, fromPeerId, signalType, payload, occurredAt	A WebRTC signal forwarded from the other peer.
error	code, message, requestId?	A protocol error for the connection or a specific request.

Protocol error codes

unsupported_message

socket_not_registered

already_connected

invalid_reconnect_request

call_not_found

peer_not_found

invalid_reconnect_token

peer_exists

call_full

not_connected

invalid_signal_request

target_not_found

target_unavailable

Call snapshot

Most server-to-client messages include a call object with the current in-memory signaling state.

JSON

{
  "callId": "550e8400-e29b-41d4-a716-446655440000",
  "createdAt": "2026-05-05T10:30:00.000Z",
  "updatedAt": "2026-05-05T10:31:00.000Z",
  "peers": [
    { "peerId": "peer_a1b2c3", "status": "connected", "updatedAt": "..." },
    { "peerId": "peer_d4e5f6", "status": "disconnected", "updatedAt": "..." }
  ]
}

Room WebSocket API

Connect to the room signaling endpoint with the project public key and one fresh room token. The server replies with a room-joined message containing transport parameters and the list of peers already in the room. Room tokens are minted from your backend — see the Server SDK API reference.

Plug the returned transport parameters into mediasoup-client to handle the actual media plane.

Connect

TypeScript

const ws = new WebSocket(
  'wss://radist.tech/api/v1/sfu/signaling/ws' +
    '?publicKey=<your public key>' +
    '&roomToken=ct_abc123...'
);

Client → server messages

Type	Fields	Description
connect-transport	transportId, dtlsParameters	Complete the DTLS handshake for a send or recv transport.
produce	kind, rtpParameters, transportId?	Publish an audio or video track to the room. Server replies with produced.
consume	producerId, rtpCapabilities, transportId?	Subscribe to a remote producer. Server replies with consumer-parameters.
set-preferred-layer	consumerId, spatialLayer, temporalLayer?	Tune simulcast layer preferences for an existing consumer.
leave-room	—	Leave the current room. Closes producers/consumers and ends billing.
e2ee-announce	publicKey, keyId	Broadcast your X25519 public key and current sender key ID to all peers in the room.
e2ee-key	targetPeerId, keyId, wrappedKey, wrapIv	Deliver an ECDH-wrapped sender key to a specific peer.
e2ee-request-key	targetPeerId	Ask a specific peer to resend their latest wrapped sender key.

Server → client messages

Type	Fields	Description
room-joined	roomId, peerId, sendTransport, recvTransport, existingPeers	Initial snapshot with transport parameters and currently connected peers.
transport-connected	transportId	Acknowledges a successful connect-transport request.
produced	producerId, kind	Acknowledges a produce request and assigns a producer id.
new-producer	peerId, producerId, kind	Another peer started producing. Call consume to subscribe.
consumer-parameters	peerId, consumerId, producerId, kind, rtpParameters	Reply to a consume request with the rtpParameters needed by mediasoup-client.
peer-left	peerId	A peer disconnected or left the room.
error	code?, message	A protocol error for the connection or last request.
e2ee-peer-announced	fromPeerId, publicKey, keyId	A peer broadcast their X25519 public key and sender key ID.
e2ee-peer-key	fromPeerId, keyId, wrappedKey, wrapIv	A peer delivered their wrapped sender key to you.
e2ee-key-requested	fromPeerId	A peer is requesting that you resend your latest wrapped sender key.