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v52

OpenAPI 3.1.0raw.githubusercontent.com2026-07-311,1941,9384.1 MB
Speech To Text over WebSockets

Speech to text over WebSocket

Open a WebSocket connection to stream audio and receive transcriptions in real-time. Authentication is provided via the standard Authorization: Bearer <API_KEY> header.

Supported engines: Azure, Deepgram, Google, Telnyx, xAI, Speechmatics, Soniox, Parakeet, Humain, Reson8.

Connection flow:

  1. Open WebSocket with query parameters specifying engine, input format, and language.
  2. Send binary audio frames (mp3/wav format).
  3. Receive JSON transcript frames with transcript, is_final, and confidence fields.
  4. Close connection when done.
get/speech-to-text/transcription

Query parameters

transcription_engine'Azure' | 'Deepgram' | 'Google' | 'Telnyx' | 'xAI' | 'Speechmatics' | 'Soniox' | 'Parakeet' | 'Humain' | 'Reson8' required

The transcription engine to use for processing the audio stream.

input_format'mp3' | 'wav' required

The format of input audio stream.

languagestring

The language spoken in the audio stream.

interim_resultsboolean

Whether to receive interim transcription results.

'fast'
OR
'deepgram/nova-2' | 'deepgram/nova-3'
OR
'latest_long' | 'latest_short' | 'command_and_search' | 'phone_call' | 'video' | 'default' | 'medical_conversation' | 'medical_dictation'
OR
'openai/whisper-tiny' | 'openai/whisper-large-v3-turbo'
OR
'xai/grok-stt'
OR
'speechmatics/standard'
OR
'soniox/stt-rt-v4'
OR
'nvidia/parakeet-v3'
OR
'humain/realtime'
OR
'reson8/turns'

The specific model to use within the selected transcription engine.

endpointinginteger

Silence duration (in milliseconds) that triggers end-of-speech detection. When set, the engine uses this value to determine when a speaker has stopped talking. Supported by xAI, Deepgram, Google, Speechmatics, and Soniox. Soniox accepts values between 500 and 3000. Other engines may not support this parameter.

redactstring

Enable redaction of sensitive information (e.g., PCI data, SSN) from transcription results. Supported values depend on the transcription engine.

keytermstring

A key term to boost in the transcription. The engine will be more likely to recognize this term. Can be specified multiple times for multiple terms.

keywordsstring

Comma-separated list of keywords to boost in the transcription. The engine will prioritize recognition of these words.

Response

WebSocket upgrade successful — this response is not returned directly. See 101 for frame documentation.