API Docs

The YoutubeDownload4Free backend exposes two endpoints: one to read media metadata, and one to download a converted file.

Overview

All endpoints are served from the same origin. Responses are JSON unless you're downloading a file, which streams the binary directly with a Content-Disposition attachment header.

POST /api/info

Fetch the title, thumbnail, duration, and available formats for a supported link.

Request body

{
  "url": "https://www.youtube.com/watch?v=..."
}

Example

curl -X POST /api/info \
  -H "Content-Type: application/json" \
  -d '{"url":"https://youtu.be/aqz-KE-bpKQ"}'

Response (shape)

{
  "id": "aqz-KE-bpKQ",
  "title": "Big Buck Bunny",
  "uploader": "Blender",
  "durationSeconds": 635,
  "thumbnail": "https://...",
  "platform": "youtube",
  "webpageUrl": "https://...",
  "formats": [
    {
      "id": "137",
      "selector": "137+bestaudio[ext=m4a]/137",
      "ext": "mp4",
      "kind": "video",      // "video" | "audio" | "other"
      "label": "1080p",
      "detail": "mp4 · 60fps",
      "filesizeApprox": 245690000
    }
  ]
}

GET /api/download

Download and convert a single format. The values come straight from a format object returned by /api/info.

Query parameters

  • url — the source page URL
  • selector — the yt-dlp format selector from the format object
  • ext — target container, e.g. mp4
  • kindvideo, audio, or other
  • title — used for the download filename
  • convert — optional; set to mp3 to extract audio as MP3
  • quality — optional MP3 bitrate: 128, 192, 256, or 320

Example — 320kbps MP3

GET /api/download?url=https://youtu.be/aqz-KE-bpKQ
  &selector=bestaudio/best
  &ext=mp3&kind=audio&convert=mp3&quality=320
  &title=My%20Track

The response streams the file. High-resolution video formats are merged with audio on the server before the download begins, so the first byte may take several seconds for large files.

Errors

Failed requests return a JSON body with an error message and an appropriate HTTP status (for example 400 for a bad request or 422 if the media can't be read).

Fair use

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