Audio transcription API: speech to text with Whisper large-v3-turbo

$0.01 per call · failed calls are never charged · no account or subscription: pay per call with a card key or USDC

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 to use it

Guide: Speech to text API

Buy credits by card (from $1) Example result (JSON)

Inputs

NameTypeDescription
url (required)stringAbsolute http(s) URL of an audio file (max 5 MB)

Request

Over HTTP, with a card key from /credits:

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

Without a key, the same URL answers 402 Payment Required with x402 and MPP terms, so an agent with a wallet pays per call in USDC (Base, Polygon, Arbitrum or Solana over x402; Base or Tempo over MPP) and retries.

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"
}

From an AI agent (MCP)

Add the MCP server to Claude, Cursor or any MCP client. This tool is transcribe, and the first 25 successful calls are free:

https://tools.funwords.eu/mcp

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 $0.01; failed calls are not charged. This tool is not in the free calls; pay with card credits (from $1; the key goes in an Authorization header or, for clients that can only fetch a URL, as api_key= in the URL) or per call in USDC over x402 or MPP. No account is needed.

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