Speech-to-text

Transcribe audio to text using OpenAI (gpt-4o-mini-transcribe). Provide a URL to an audio file (mp3, wav, m4a, etc.) and get back the transcript. No API key needed; pay per call via x402. Max 5 minutes of audio, 25 MB file size.

Input

Field	Type	Description
url *	string	URL of the audio file to transcribe (mp3, wav, m4a, ogg, flac, webm)
language	string	Optional ISO-639-1 language code (e.g. 'en', 'es', 'fr') for better accuracy

Example output

{
  "model": "gpt-4o-mini-transcribe",
  "provider": "openai",
  "text": "Hello, this is a sample transcription.",
  "language": "en",
  "duration": 3.5
}

Try it — see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/transcribe \
  -H "Content-Type: application/json" \
  -d '{"url":"https://example.com/audio.mp3"}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/transcribe", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "url": "https://example.com/audio.mp3"
  }),
});

Wallet-only. This tool reaches the network/browser/storage, so it is paid in USDC via x402 (no proof-of-work tier).

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