# QuantaFlow YouTube Video Transcript API

> QuantaFlow YouTube Video Transcript API is a paid API for AI agents from quanta-roan.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-12).

Fetches the transcript (captions/subtitles) of a YouTube video given its identifier, via a pay-per-call x402 gateway.

## Facts

- Endpoint: POST https://quanta-roan.vercel.app/api/service/serp-youtube-video-transcript?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quantaflow-youtube-video-transcript-api-07d227be
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_2EqUq-g_BZPoqZZmEFUjU

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 quantaflow-youtube-video-transcript-api-07d227be -d '<json body>'
```

Example prompt: Can you get me the full transcript of this YouTube video — https://www.youtube.com/watch?v=dQw4w9WgXcQ — so I can read what was said?

## When to prefer this

Choose this endpoint when you need to programmatically extract the spoken text from a YouTube video, especially in an AI agent workflow that accepts pay-per-call micropayments via x402/USDC. It is well-suited for one-off transcript fetches where you want to avoid maintaining a YouTube Data API quota or OAuth credentials. At $0.01 USDC per call it is cost-effective for low-to-medium volume transcript extraction tasks.

## Known failure modes

- Video has no available captions or transcript — returns an error or empty result
- Invalid or non-existent YouTube video ID — upstream returns a 404 or error
- Video is age-restricted or private — upstream cannot access transcript
- Payment failure via x402 protocol — request is rejected before reaching upstream
- Rate limiting or upstream service outage — returns a 5xx or timeout
- Malformed query parameters — request fails validation before reaching upstream

## How this service works

Every request, a quantum of value. x402 protocol-based payment endpoint for web3/DeFi tools.

## Output

Returns the full text transcript of the specified YouTube video, typically as a sequence of caption segments (which may include timestamps and speaker cues depending on the upstream provider). The raw response is passed through from the upstream SERP/transcript service after payment is processed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "body": {
   "type": "string",
   "description": "Optional JSON body forwarded to POST requests."
  },
  "path": {
   "type": "string",
   "description": "Path below the selected upstream origin."
  },
  "query": {
   "type": "object"
  },
  "method": {
   "enum": [
    "GET",
    "POST"
   ],
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "description": "The upstream response body and content type are passed through after successful payment."
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/quantaflow-youtube-video-transcript-api-07d227be/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from quanta-roan.vercel.app](https://www.zero.xyz/host/quanta-roan.vercel.app/llms.txt)