Speech to text API

From $0.01 per successful call · failed calls are never charged · no account needed · Markdown version: /guides/speech-to-text-api.md

Transcribe speech from an audio file at a public URL using Whisper large-v3-turbo. Returns the transcript text, detected language, duration and word count. Accepts common formats such as MP3, WAV, M4A and OGG up to 5 MB. Use for voice notes, podcast clips, meeting snippets and voice messages.

When an agent wants this

Speech to text, transcribe audio: Whisper transcription of an audio file $0.01

Transcribe speech from an audio file at a public URL using Whisper large-v3-turbo. Returns the transcript text, detected language, duration and word count. Accepts common formats such as MP3, WAV, M4A and OGG up to 5 MB. Use for voice notes, podcast clips, meeting snippets and voice messages.

Inputs: url (required): Absolute http(s) URL of an audio file (max 5 MB).

Not in the free calls (it costs capacity per call); pay from the first call.

With a card key from /credits, in a header or, when your client can only fetch a URL, in the URL:

curl -H "Authorization: Bearer adt_…" "https://tools.funwords.eu/transcribe?url=https%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FSpecial%3AFilePath%2FEn-us-hello.ogg"
curl "https://tools.funwords.eu/transcribe?url=https%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FSpecial%3AFilePath%2FEn-us-hello.ogg&api_key=adt_…"

Without a key the same URL answers 402 Payment Required with x402 and MPP terms, so a wallet client pays USDC per call and retries. Over MCP (https://tools.funwords.eu/mcp) this tool is transcribe.

Example result
{
  "url": "https://commons.wikimedia.org/wiki/Special:FilePath/En-us-hello.ogg",
  "text": "Hello!",
  "language": "en",
  "durationSeconds": 0.487625,
  "wordCount": 1,
  "model": "@cf/openai/whisper-large-v3-turbo"
}

Tool page, inputs and limits

Questions

Which formats and size?

Common formats such as MP3, WAV, M4A and OGG at a public URL, up to 5 MB.

How do I pay?

Each successful call costs the tool's price; failed calls are not charged. Then pay with card credits from $1 (the key goes in an Authorization header or as api_key= in the URL) or per call in USDC over x402 or MPP. No account is needed.