Preview Agent Session

{
  "createDailyRoom": true,
  "dailyRoomProperties": {
    "start_video_off": true
  },
  "dailyMeetingTokenProperties": {
    "is_owner": true,
    "user_name": "Preview Tester"
  },
  "body": {
    "test_context": "agent-editor-preview"
  }
}

{
  "dailyRoom": "https://your-domain.daily.co/room-name",
  "dailyToken": "eyJhbGciOi...",
  "sessionId": "call_a1b2c3d4e5f6"
}

POST

api

start

{agent_id}

{
  "createDailyRoom": true,
  "dailyRoomProperties": {
    "start_video_off": true
  },
  "dailyMeetingTokenProperties": {
    "is_owner": true,
    "user_name": "Preview Tester"
  },
  "body": {
    "test_context": "agent-editor-preview"
  }
}

{
  "dailyRoom": "https://your-domain.daily.co/room-name",
  "dailyToken": "eyJhbGciOi...",
  "sessionId": "call_a1b2c3d4e5f6"
}

Use preview mode to test an agent directly from the dashboard (or your own client) without placing a PSTN call.

What this endpoint does

POST /api/start/{agent_id} creates a temporary preview session and returns connection details:

dailyRoom: temporary room URL
dailyToken: temporary participant token
sessionId: Butter call/session ID (call_...)

This is the customer-facing session start flow used by the agent preview UI.

string

required

Agent ID to preview (format: agent_...).

boolean

When true, requests creation of a room for this preview session.

object

Optional room configuration passed through to the preview room provider.

object

Optional token configuration for the preview participant.

object

Optional custom payload forwarded to the preview bot runtime.

Response

string

Preview room URL.

string

Preview participant token.

string

Preview session call ID (call_...).

{
  "createDailyRoom": true,
  "dailyRoomProperties": {
    "start_video_off": true
  },
  "dailyMeetingTokenProperties": {
    "is_owner": true,
    "user_name": "Preview Tester"
  },
  "body": {
    "test_context": "agent-editor-preview"
  }
}

{
  "dailyRoom": "https://your-domain.daily.co/room-name",
  "dailyToken": "eyJhbGciOi...",
  "sessionId": "call_a1b2c3d4e5f6"
}

Offer/Answer testing flow (custom WebRTC clients)

If you are building a custom WebRTC test client, Butter preview also supports an offer/answer exchange:

Create an SDP offer from your client.
Send the offer to the preview API.
Apply the returned SDP answer in your client.
Continue ICE candidate exchange until connected.

This docs section intentionally stays at flow level. It does not expose low-level transport internals.

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Introduction

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Preview & Voice Selection

Integrations

API Keys

Preview Agent Session

What this endpoint does

Response

Offer/Answer testing flow (custom WebRTC clients)

​What this endpoint does

​Response

​Offer/Answer testing flow (custom WebRTC clients)

What this endpoint does

Response

Offer/Answer testing flow (custom WebRTC clients)