AsyncAPI channel · Vapi · Vapi Realtime API (WebSocket Transport + Server URL Events)

server-url/assistant-speech-started

Real-time word-level timing for assistant speech, opt-in via `serverMessages`. Variants: ElevenLabs word-alignment, Minimax word-progress, or text-only (other providers).

Open source AsyncAPI → All Vapi channels Vapi provider profile
Provider: Vapi AsyncAPI: v2.6.0 Spec: Vapi Realtime API (WebSocket Transport + Server URL Events) Operations: 1 Messages: 1

Channel address

server-url/assistant-speech-started

Operations

subscribe server-url/assistant-speech-started

Messages

AssistantSpeechStarted
assistant.speechStarted
Content-Type:

About AsyncAPI

The AsyncAPI specification describes event-driven APIs the way OpenAPI describes request/response APIs. A channel is the named pipe — a webhook URL, a Kafka topic, a WebSocket route, an MQTT subject — that producers and consumers publish or subscribe to. Each channel carries one or more messages with structured payloads, and an operation declares whether a given party sends or receives on that channel.

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