# x402Factory.ai Speech-to-Text (Base/USDC)

> x402Factory.ai Speech-to-Text (Base/USDC) is a paid API for AI agents from x402factory.ai, paid per call via x402, $0.6/call, status unknown (last checked 2026-09-14).

Transcribes audio from a YouTube video or direct audio file URL into text, charging 0.01 USDC per minute via x402 micropayment on Base.

## Facts

- Endpoint: POST https://x402factory.ai/base/stt
- Price: $0.6/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402factory-ai-speech-to-text-base-usdc-938f2d50
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5D4x48IkdaZjvrlyPIhjD

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 x402factory-ai-speech-to-text-base-usdc-938f2d50 -d '<json body>'
```

Example prompt: Can you transcribe this YouTube video for me? Here's the URL: https://www.youtube.com/watch?v=dQw4w9WgXcQ — I need the full spoken transcript.

## When to prefer this

Use this endpoint when you need to transcribe audio from a YouTube video or a direct audio file URL and want per-minute micropayment pricing (0.01 USDC/minute) via x402 on Base rather than a traditional API key subscription. Ideal for pay-as-you-go transcription of varying-length content without upfront commitment.

## Known failure modes

- Invalid or inaccessible YouTube URL/ID returns an error with ok=false
- Audio file URL is unreachable or not a supported format
- Payment insufficient for the actual audio duration — discovery quote may underestimate for long content
- Called without a URL returns a discovery quote (0.60 USDC upper bound) rather than a real transcript
- Network timeout downloading large audio files

## How this service works

Base speech-to-text endpoint using x402 payments. Provide either a YouTube URL/ID or a direct audio file URL; the server downloads the audio, runs speech-to-text, and returns the transcript text. Pricing: 0.01 USDC per started minute of audio, computed from the estimated duration and charged upfront via x402. Default discovery price without a specific URL is 0.60 USDC as an upper-bound quote. When called without a specific URL, the endpoint returns a default discovery quote. Clients should re-run discovery with a concrete URL to get an exact quote based on the real audio duration.

## Output

Returns a JSON object with ok=true on success, the full transcript as a plain text string in the 'text' field, the source type used ('youtube' or 'file_url'), the resolved URL or video ID processed, the audio duration in seconds and rounded-up minutes, and the exact USDC price charged for the call.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "youtube": {
   "type": "string",
   "description": "YouTube video URL (e.g. https://www.youtube.com/watch?v=...) or 11-character video ID. For paid calls, either youtube or file_url is required."
  },
  "file_url": {
   "type": "string",
   "description": "Direct URL to an audio file (e.g. .mp3, .webm). Must be an http(s) URL. For paid calls, either youtube or file_url is required."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "ok": {
  "type": "boolean",
  "description": "True on success."
 },
 "text": {
  "type": "string",
  "description": "Full transcript text returned by the speech-to-text engine (top-level 'text' field)."
 },
 "action": {
  "type": "string",
  "description": "Action performed. For this endpoint: 'stt'."
 },
 "source": {
  "type": "string",
  "description": "Source type used for transcription: 'youtube' or 'file_url'."
 },
 "file_url": {
  "type": "string",
  "description": "Direct file URL that was processed when source = 'file_url'."
 },
 "video_id": {
  "type": "string",
  "description": "YouTube video ID that was processed."
 },
 "price_usdc": {
  "type": "number",
  "description": "Price charged for this call in USDC (6 decimals). Computed as 0.01 USDC per started minute of audio."
 },
 "youtube_url": {
  "type": "string",
  "description": "Resolved YouTube URL that was processed."
 },
 "duration_minutes": {
  "type": "number",
  "description": "Duration rounded up to whole minutes, used for pricing (0.01 USDC per minute)."
 },
 "duration_seconds": {
  "type": "number",
  "description": "Audio duration in seconds when available (YouTube metadata or estimated from file size)."
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402factory-ai-speech-to-text-base-usdc-938f2d50/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402factory.ai](https://www.zero.xyz/host/x402factory.ai/llms.txt)