# FastX402 Audio Transcription

> FastX402 Audio Transcription is a paid API for AI agents from fastx402.tools, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-17).

Transcribes an audio file (mp3, m4a, wav, ogg, webm, flac) at a given URL into text with timestamps and language detection, paid per-call in USDC via x402.

## Facts

- Endpoint: GET https://fastx402.tools/transcribe?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-17
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastx402-audio-transcription-3cee29fe
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_WmDqnSeL1BhHH7lpdbity

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability fastx402-audio-transcription-3cee29fe
```

Example prompt: Can you transcribe this podcast episode for me? The audio is at https://example.com/episode42.mp3 — auto-detect the language and give me the full text with timestamps.

## When to prefer this

Choose this endpoint when you need fast, pay-per-call audio-to-text transcription without setting up an API key or account. It's ideal for AI agents that need occasional or sporadic transcription of publicly accessible audio files in multiple formats and languages, billed precisely per request in USDC on Base. Prefer it over subscription-based services when cost predictability at low volume matters, or when you need automatic language detection alongside timestamped segments.

## Known failure modes

- Unreachable or invalid audio URL returns an error (file must be a publicly accessible http/https link)
- Unsupported file format (only mp3, m4a, wav, ogg, webm, flac accepted) causes a rejection
- Very long audio files may exceed processing limits or increase latency significantly
- Incorrect language code provided causes degraded transcription quality
- Payment failure via x402 (insufficient USDC balance or unsupported wallet) blocks the request

## How this service works

146 pay-per-call tools for AI agents, from $0.001 per request in USDC on Base or Solana with x402. No account, no API key.

## Output

A JSON object containing the full transcript text, the detected or specified language code (e.g. 'en', 'tr'), an array of timed segments each with start time, end time, and segment text, and the total audio duration in seconds.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string",
       "description": "Absolute http(s) URL of an mp3, m4a, wav, ogg, webm or flac file"
      },
      "lang": {
       "type": "string",
       "description": "auto (default) or a two-letter language code such as tr or en"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "text": {
       "type": "string"
      },
      "language": {
       "type": "string"
      },
      "segments": {
       "type": "array",
       "items": {
        "type": "object",
        "properties": {
         "end": {
          "type": "number"
         },
         "text": {
          "type": "string"
         },
         "start": {
          "type": "integer"
         }
        }
       }
      },
      "duration_s": {
       "type": "integer"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "text": "And so my fellow Americans ask not what your country can do for you, ask what you can do for your country.",
  "language": "en",
  "segments": [
   {
    "end": 10.5,
    "text": "And so my fellow Americans ask not what your country can do for you, ask what you can do for your country.",
    "start": 0
   }
  ],
  "duration_s": 11
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastx402-audio-transcription-3cee29fe/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fastx402.tools](https://www.zero.xyz/host/fastx402.tools/llms.txt)