Transcribe an audio file to text. POST { url, language?, diarize? } — the audio is fetched from your URL (wav, mp3, m4a/aac, ogg/opus, flac, webm; up to 15 MB and 15 minutes per call — split longer recordings and call once per segment). Returns the full punctuated transcript, overall confidence, audio duration, detected or specified language (BCP-47, e.g. "en", "es"), word-level timestamps with confidences, and — with diarize=true — speaker-segmented utterances (who said what, when). High-accuracy speech recognition for meeting notes, podcast processing, voicemail handling, and media monitoring.
/api/transcribe/audioPAYMENT-SIGNATURE.The audio API is a pay-per-call transcribe endpoint built for AI agents and autonomous software. Transcribe an audio file to text.
There is no signup and no API key. An agent (or any HTTP client) hits the endpoint, receives an x402 "402 Payment Required" challenge, signs a sub-cent USDC payment on Base or Solana, and retries — the data comes back on the paid request. That makes it a drop-in audio data source for an agent tool-use loop, an MCP host, or a backend that needs transcribe data on demand without onboarding to yet another vendor portal.
| Name | Type | Description |
|---|---|---|
urlrequired | string | Public audio URL. Caps: 15 MB, 15 minutes. max 2048 chars · uri |
language | string | match ^[a-z]{2,3}(-[A-Za-z0-9]{2,8})?$ |
diarize | boolean |
# 1. Probe the endpoint with no auth — receive 402 with PaymentRequirements
curl -sS -X POST 'https://2s.io/api/transcribe/audio' \
-H 'Content-Type: application/json' \
-d '{"url":"https://example.com","language":"example","diarize":false}'
# 2. Sign the EIP-3009 transferWithAuthorization for the advertised price +
# payTo from the 402 envelope, then retry with PAYMENT-SIGNATURE:
curl -sS -X POST 'https://2s.io/api/transcribe/audio' \
-H 'Content-Type: application/json' \
-H 'PAYMENT-SIGNATURE: <base64-json-payload>' \
-d '{"url":"https://example.com","language":"example","diarize":false}'
# Or just use the canonical runner — it handles the whole loop:
# EVM_PRIVATE_KEY=0x... node --env-file=.env.local \
# --experimental-strip-types scripts/x402-pay.ts \
# 'https://2s.io/api/transcribe/audio'import { TwoS } from '@2sio/sdk'
const client = new TwoS({
privateKey: process.env.EVM_PRIVATE_KEY as `0x${string}`,
})
const result = await client.transcribe.audio({
"url": "https://example.com",
"language": "example",
"diarize": false
})
console.log('endpoint:', result.endpoint)
console.log('cost:', result.costUsd, 'USDC')
console.log('tx:', result.settlement?.txHash)
console.log('data:', result.data)import os
from twosio import TwoS
client = TwoS(private_key=os.environ["EVM_PRIVATE_KEY"])
result = client.transcribe.audio(url="https://example.com", language="example", diarize=False)
print("endpoint:", result.endpoint)
print("cost:", result.cost_usd, "USDC")
print("tx:", (result.settlement or {}).get("tx_hash"))
print("data:", result.data)// 1. Add @2sio/mcp to your MCP host config (Claude Desktop example below).
// EVM_PRIVATE_KEY funds x402 payments per call.
// claude_desktop_config.json
{
"mcpServers": {
"2sio": {
"command": "npx",
"args": ["-y", "@2sio/mcp"],
"env": { "EVM_PRIVATE_KEY": "0x..." }
}
}
}
// 2. Once the server is running, agents call this tool via standard MCP:
{
"jsonrpc": "2.0",
"id": 1,
"method": "tools/call",
"params": {
"name": "transcribe.audio",
"arguments": {
"url": "https://example.com",
"language": "example",
"diarize": false
}
}
}| Field | Type | Description |
|---|---|---|
ok | boolean | one of: true |
items | array | |
total | integer | Total matching rows upstream; null when unknown. |
source | object | |
meta | object |
{
"ok": true,
"items": [
{
"transcript": "example",
"confidence": 1,
"durationSeconds": 1,
"language": "example",
"words": [
{
"word": "example",
"start": 1,
"end": 1,
"confidence": 1,
"speaker": 1
}
],
"utterances": [
{
"speaker": 1,
"start": 1,
"end": 1,
"text": "example"
}
]
}
],
"total": 1,
"source": {
"provider": "example",
"url": "example",
"license": "example"
},
"meta": {
"wordCount": 1
}
}