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Speech-to-Text

Payment wires: every paid endpoint accepts x402 and MPP (Machine Payments Protocol) on the same 402 - see Paying with x402 and Paying with MPP. Agent402 is the applied layer of Agentic Finance: agents that pay and get paid on their own.

Acceptable use. Hosted-instance traffic is governed by the Terms of Service - including a generative-content acceptable-use policy - and by the upstream model providers' usage policies. Wallets used for prohibited content are blocked before settlement. Outputs are generated by third-party models from your inputs; you are responsible for how you use them.

Two tiers of audio transcription, paywalled via x402. Provide a URL to an audio file, get back the transcript with language detection and duration. The operator's OPENAI_API_KEY handles the default path; diarize: true runs on OPENROUTER_API_KEY.

Tiers

Endpoint Price Model Max duration
POST /api/transcribe $0.03 gpt-transcribe 4 min
POST /api/transcribe-pro $0.10 gpt-transcribe 10 min

Both tiers run the same model and differ only in the duration cap.

Speaker labels and word timestamps

Add "diarize": true (or a diarize=true form field on /v1/audio/transcriptions) to transcribe with ElevenLabs Scribe v2 instead, at the same price and cap. The answer adds speakers (how many were heard) and words, each with start, end and a speaker number:

{ "model": "elevenlabs/scribe-v2", "provider": "openrouter", "text": "Hello there. Hi.",
  "language": "eng", "duration": 1.0, "speakers": 2,
  "words": [ { "word": "Hello", "start": 0, "end": 0.3, "speaker": 0 },
             { "word": "there.", "start": 0.3, "end": 0.5, "speaker": 0 },
             { "word": "Hi.", "start": 0.6, "end": 0.9, "speaker": 1 } ] }

Both tiers are wallet-only - every call burns real upstream transcription credit. See Security Model.

Supported audio formats

mp3, m4a, wav, ogg, flac, webm (max 25 MB). mp4, mpeg and mpga files are accepted too when their duration can be read; one whose duration cannot be read answers 422 and is not charged on x402.

Request / Response

// Request
{ "url": "https://agent402.tools/fixtures/sample-audio.wav", "language": "en" }

// Response
{ "model": "gpt-transcribe", "provider": "openai",
  "text": "Hello, this is a sample transcription.",
  "language": "en", "duration": 3.5 }

Only url is required. language (ISO-639-1 code) is optional but improves accuracy.

See also