fundownloader-link-mcp

A local, read-only Model Context Protocol server that validates and canonicalizes Spotify track/playlist, Instagram post/reel, and Twitter/X status URLs.

It parses links. It does not fetch metadata, check whether content exists, or download media.

Why this exists

Agents paste media links constantly, and the same track arrives in a dozen forms:

https://open.spotify.com/track/4uLU6hMCjMI75M1A2tKUQC
https://open.spotify.com/intl-de/track/4uLU6hMCjMI75M1A2tKUQC?si=abc123
https://open.spotify.com/embed/track/4uLU6hMCjMI75M1A2tKUQC
spotify:track:4uLU6hMCjMI75M1A2tKUQC

Without normalization, an agent stores the same track five times, or retypes a URL and gets it wrong. This server turns any supported form into one canonical URL, deterministically, before the model reasons about it.

Related MCP server: io.github.mgdsn/verify-api-mcp

Requirements

• Node.js 22.12+

• Any MCP client (Claude Desktop, Cursor, VS Code, Cline, Windsurf, etc.)

Install

From source:

git clone https://github.com/boddapQ/fundownloader-link-mcp.git
cd fundownloader-link-mcp
npm install --ignore-scripts

Then add it to your MCP client configuration:

{
  "mcpServers": {
    "fundownloader-links": {
      "command": "node",
      "args": ["/absolute/path/to/fundownloader-link-mcp/server.mjs"]
    }
  }
}

Once published to npm (tracked in #1):

{
  "mcpServers": {
    "fundownloader-links": {
      "command": "npx",
      "args": ["-y", "fundownloader-link-mcp"]
    }
  }
}

Tool

normalize_media_link

Returns JSON as text:

{
  "type": "track",
  "id": "4uLU6hMCjMI75M1A2tKUQC",
  "url": "https://open.spotify.com/track/4uLU6hMCjMI75M1A2tKUQC",
  "platform": "spotify",
  "website": "https://fundownloader.online",
  "availabilityChecked": false
}

Invalid input returns isError: true with a { "error": "..." } payload.

Supported URL formats

Deliberately rejected

• spotify.link short links — resolving them requires a network call, which this server does not make. You get an explicit error instead of a wrong canonical URL.

• Albums and artist pages — not track- or playlist-level.

• Private/authenticated URLs — credentials in the URL, non-default ports, and non-HTTPS schemes are rejected.

• Unsupported platforms — tiktok, youtube, etc. return an error rather than a guess.

HTTP API

The same logic powers a free, keyless, CORS-enabled endpoint:

curl --get 'https://fundownloader.online/api/v1/link' \
  --data-urlencode 'url=https://open.spotify.com/track/4uLU6hMCjMI75M1A2tKUQC'

Docs: https://fundownloader.online/developers

Use as a library

The parser has no MCP dependency and works standalone:

import { downloadReference } from 'fundownloader-link-mcp/validation';

downloadReference('https://open.spotify.com/intl-de/track/4uLU6hMCjMI75M1A2tKUQC?si=abc');
// { type: 'track', id: '4uLU6...', url: 'https://open.spotify.com/track/4uLU6...' }

Development

npm install --ignore-scripts
npm test

Tests use the built-in node:test runner and cover locale prefixes, URI form, short links, tracking parameters, Instagram path variants, and X/Twitter host normalization.

Privacy and security

• No network requests after the tool call — parsing is local and synchronous.

• No API key, account, cookies, or telemetry.

• No media is fetched, stored, or redistributed.

• Read-only: the tool cannot write files, execute commands, or call other services.

• Canonicalization does not grant any rights to the linked content.

License

MIT. See LICENSE.

Not affiliated with Spotify, Instagram, X, or YouTube.