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

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

Speech to text API: code samples in curl, Python and Node, and monthly plans.

Transcribe speech from an audio file at a public URL, or uploaded in a POST body, using Whisper large-v3-turbo. Returns the transcript text, detected language, duration and word count; subtitles=srt or vtt adds subtitle text and timestamps=true adds timed segments and words. Accepts common formats such as MP3, WAV, M4A and OGG up to 5 MB, in 90+ languages. Use for voice notes, podcast clips, meeting snippets, subtitles and voice messages.

When to use it

Transcribe voice notes, podcast clips, meeting snippets and voice messages
Get the transcript, detected language, duration and word count

Guide: Speech to text API

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

Inputs

Name	Type	Description
`url` (required)	string	Absolute http(s) URL of an audio file (max 5 MB); or POST the file itself (raw body, multipart `file` part, or base64 in JSON)
`subtitles`	string	srt or vtt: also return subtitle text
`timestamps`	string	true: also return timed segments and words
`language`	string	Spoken language code such as en, sv or de (default: detected)

Request

Over HTTP, with a card key from /credits:

curl -H "Authorization: Bearer adt_…" "https://glyphcall.com/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://glyphcall.com/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.