# YouTube Transcript API — Melchior Labs

> YouTube Transcript API — Melchior Labs is a paid API for AI agents from transcript.melchiorlabs.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-23).

Fetches structured transcripts from public YouTube videos, returning full text, timestamped chunks, and citation URLs, billed per request via x402.

## Facts

- Endpoint: POST https://transcript.melchiorlabs.com/v1/youtube/transcript?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-23
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/youtube-transcript-api-melchior-labs-19e81217
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bVC_G3klPDEn-UlkAiusE

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 youtube-transcript-api-melchior-labs-19e81217 -d '<json body>'
```

Example prompt: Can you grab the full transcript of this YouTube video — https://www.youtube.com/watch?v=dQw4w9WgXcQ — in English, broken into chunks of about 2400 characters each, with timestamp citations for every chunk?

## When to prefer this

Choose this endpoint when you need structured, agent-ready YouTube transcripts with timestamped chunks and citation URLs in a single pay-per-call request, especially when integrating into LLM pipelines that require grounded references back to specific video moments. Prefer it over generic scraping when you need clean text segmentation with configurable chunk sizes and built-in token usage estimates.

## Known failure modes

- Video is private or age-restricted — no transcript returned
- No captions available in requested language — error or fallback to auto-generated
- Invalid or non-YouTube URL format — validation error
- Video has disabled captions entirely — no transcript available
- Network timeout fetching captions from YouTube — request error

## How this service works

Pay per request for structured YouTube transcripts, lexical passage search, chunks, and timestamp citations over x402.

## Output

Returns a JSON object containing: full transcript text with language and source info (manual vs auto-generated), an array of timestamped chunks each with start/end seconds and a citation URL deep-linking to that moment in the video, video metadata (title, duration, ID), and usage stats (character count, estimated tokens, chunk count, cache status).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "pattern": "^https://(?:www\\.|m\\.)?(?:youtube\\.com|youtu\\.be)/",
   "description": "Public youtube.com or youtu.be video URL"
  },
  "language": {
   "type": "string",
   "default": "en",
   "description": "Caption language code, such as en or es"
  },
  "includeText": {
   "type": "boolean",
   "default": true
  },
  "preferManual": {
   "type": "boolean",
   "default": true
  },
  "includeSegments": {
   "type": "boolean",
   "default": true
  },
  "maxChunkCharacters": {
   "type": "integer",
   "default": 2400,
   "maximum": 8000,
   "minimum": 400
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "usage": {
   "cache": "miss",
   "characters": 4200,
   "chunkCount": 2,
   "estimatedTokens": 1050
  },
  "video": {
   "id": "dQw4w9WgXcQ",
   "url": "https://www.youtube.com/watch?v=dQw4w9WgXcQ",
   "title": "Video title",
   "durationSeconds": 213
  },
  "chunks": [
   {
    "text": "Agent-ready context...",
    "index": 0,
    "citation": {
     "url": "https://www.youtube.com/watch?v=dQw4w9WgXcQ&t=0s",
     "label": "0:00–0:35"
    },
    "endSeconds": 35,
    "startSeconds": 0
   }
  ],
  "requestId": "0b0ef10e-ff50-4a45-9c4e-b7344aa93f63",
  "transcript": {
   "text": "Transcript text...",
   "source": "manual",
   "language": "en",
   "segmentCount": 42
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/youtube-transcript-api-melchior-labs-19e81217/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from transcript.melchiorlabs.com](https://www.zero.xyz/host/transcript.melchiorlabs.com/llms.txt)