# MDN MCP Server

> An experimental MCP server by Mozilla that gives LLMs and coding agents reliable, up-to-date access to MDN's web platform documentation, search, and browser compatibility data.

The MDN MCP server is an experimental open-source project from Mozilla that exposes MDN Web Docs content — including search, documentation, and browser compatibility data — to LLMs and coding agents via the Model Context Protocol (MCP). It is licensed under the Mozilla Public License 2.0 and hosted publicly on GitHub under the `mdn` organization. The project was created in October 2025 and has been actively maintained through mid-2026.

## What It Is

The MDN MCP server is a JavaScript-based MCP server that connects AI coding tools and agents to MDN's authoritative web platform documentation. Its stated goal is to give LLMs a reliable, current source of web standards information rather than relying on potentially outdated training data. It can be run as a remote hosted service at `mcp.mdn.mozilla.net` or self-hosted locally.

## How It Works

The server implements the MCP server protocol, making MDN's content queryable by any MCP-compatible client. Developers add it to their tool of choice — the README demonstrates integration with Claude Code using a single `claude mcp add` command. Two transport modes are supported:

- **Remote**: Connect directly to Mozilla's hosted endpoint (`https://mcp.mdn.mozilla.net/`)
- **Local**: Clone the repo, run `npm install` and `npm start`, then point your MCP client at `http://localhost:3002/`

A development mode (`npm run dev`) launches the MCP inspector alongside the server and enables hot-reload on file changes.

## Experimental Status and Privacy

Mozilla explicitly describes this as an experiment. The README notes that the server may be withdrawn at any time. While the experiment is running, Mozilla states it stores data about queries received, though not in a way designed to identify users. Users concerned about private information appearing in queries are advised not to use the server. An opt-out header (`X-Moz-1st-Party-Data-Opt-Out: 1`) is available for first-party analytics. Use is subject to Mozilla's Acceptable Use Policy.

## Audience and Use Case

The primary audience is web developers using AI coding assistants who want accurate, up-to-date web platform reference material surfaced directly in their LLM workflows. Rather than relying on a model's training-time snapshot of MDN content, the server provides live access to MDN's search index and browser compatibility tables — particularly useful for questions about newer APIs, cross-browser support, or recently changed specifications.

## Open-Source Lineage

The project is maintained by the `mdn` GitHub organization, which is Mozilla's home for MDN Web Docs tooling and content. It is written in JavaScript, licensed under MPL-2.0, and accepts community contributions. As of late June 2026, the repository had 150 stars and 11 forks, with active pushes continuing through that date.

## Features
- Access to MDN web platform documentation via MCP
- MDN search integration
- Browser compatibility data access
- Remote hosted server at mcp.mdn.mozilla.net
- Local self-hosting support
- MCP inspector for local development
- Hot-reload development mode
- First-party analytics opt-out header support

## Integrations
Claude Code, Any MCP-compatible LLM client

## Platforms
API, CLI

## Pricing
Open Source

## Links
- Website: https://github.com/mdn/mcp
- Documentation: https://github.com/mdn/mcp#readme
- Repository: https://github.com/mdn/mcp
- EveryDev.ai: https://www.everydev.ai/tools/mdn-mcp-server