AsyncAPI channel · Cartesia · Cartesia Realtime WebSocket API (TTS + STT)

/stt/websocket

Realtime speech-to-text without automatic turn detection. The client streams binary audio frames (100ms chunks recommended) and sends text commands (`finalize`, `close`) to control finalization; the server returns incremental and final transcript messages. The connection-level query parameters `model`, `encoding`, and `sample_rate` are required and cannot be changed mid-connection. The `/stt/turns

Open source AsyncAPI → All Cartesia channels Cartesia provider profile
Provider: Cartesia AsyncAPI: v2.6.0 Spec: Cartesia Realtime WebSocket API (TTS + STT) Operations: 2 Messages: 7

Channel address

/stt/websocket

Operations

publish
sendSttAudioAndCommands
Stream binary audio frames and send finalize/close commands.
receiveSttTranscripts
Receive incremental/final transcripts and control messages.

Messages

SttAudioFrame
Binary audio frame
Content-Type: application/octet-stream
SttFinalizeCommand
Finalize command
Content-Type: text/plain
SttCloseCommand
Close command
Content-Type: text/plain
SttTranscript
Transcript chunk
Content-Type: application/json
SttFlushDone
Finalize acknowledgement
Content-Type: application/json
SttDone
Close acknowledgement
Content-Type: application/json
SttError
Error response
Content-Type: application/json

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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