Join Event

Register an audience member into the active session and receive their attendee token

Call this endpoint when an audience member joins your show — for example, after they scan the QR code and land on the audience web page. It returns a short-lived eventToken scoped to that attendee.

Endpoint

POST /api/v1/runtime/events/{eventId}/join

Auth: Authorization: Bearer <accessToken> (your runtime client token)

Path param	Description
eventId	The event ID returned by Start Event

Request body

{
  "attendeeRef": "player_42"
}

Field	Type	Required	Description
attendeeRef	string	—	An optional identifier you assign to this attendee (e.g. username, seat number). Used for tracking — not visible to the attendee.

Response

{
  "eventId": "evt_xxxxxxxxxxxxxxxx",
  "visualId": "vis_xxxxxxxxxxxxxxxx",
  "producerUserId": "usr_xxxxxxxxxxxxxxxx",
  "tokenType": "Bearer",
  "eventToken": "eyJhbGci...",
  "expiresIn": 7200
}

Field	Description
eventToken	Attendee-scoped Bearer token. Pass this to the audience web frontend so it can authenticate audience-side API calls
expiresIn	Token lifetime in seconds

Error responses

Status	Code	Meaning
401	INVALID_RUNTIME_CLIENT	Runtime client token missing or invalid
403	EVENT_NOT_FOUND_OR_ENDED	The event doesn’t exist or has already ended
403	RUNTIME_CLIENT_NOT_AUTHORIZED	Token not authorized for this event’s visual

Typical flow

This call is usually made by the audience web frontend (the page your audience visits after scanning the QR code), not directly from Unreal Engine. The frontend calls your visual’s backend (or a serverless function you provide), which calls /join with the runtime client token and forwards the eventToken back to the attendee’s browser.

Audience scans QR code
    ↓
Audience web page loads → calls your join endpoint
    ↓
Your server: POST /runtime/events/{eventId}/join  { attendeeRef }
    ↓
Returns eventToken to the audience web page
    ↓
Audience web page uses eventToken for all subsequent audience API calls