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W3c Mcp Server

@shuji-bonji

Repository

About W3c Mcp Server

MCP Server for accessing W3C/WHATWG/IETF web specifications. Provides AI assistants with access to official web standards data including specifications, WebIDL definitions, CSS properties, and HTML elements.

#w3c#web-standards#specifications#webidl#css#html#pwa#documentation

Config

Add this server to your MCP-compatible client using the configuration below.

{
  "mcpServers": {
    "w3c": {
      "command": "npx",
      "args": [
        "-y",
        "@shuji-bonji/w3c-mcp"
      ]
    }
  }
}

Tools

11

List W3C/WHATWG/IETF web specifications with optional filtering by organization, keyword, or category

Get detailed information about a specific web specification including URLs, status, repository, and test info

Search web specifications by query string, searching in title, shortname, and description

Get WebIDL interface definitions for a specification. WebIDL defines the JavaScript APIs.

List all specifications that have WebIDL definitions available

Get CSS property definitions from a specific spec or all specs

List all CSS specifications that have property definitions available

Get HTML element definitions from a specific spec or all specs

List all specifications that have HTML element definitions available

Get all Progressive Web App (PWA) related specifications including Service Worker, Web App Manifest, Push API, Background Sync, etc.

[DEPRECATED] Returns only basic spec metadata with empty dependencies/dependents arrays (upstream web-specs does not expose dependency data). Scheduled for removal in the next major release — use get_w3c_spec instead.

Overview

What is W3c Mcp Server?

W3c Mcp Server is an MCP (Model Context Protocol) server that provides AI assistants with access to official W3C, WHATWG, and IETF web standards data, including specifications, WebIDL definitions, CSS properties, and HTML elements. It is built for developers who need programmatic access to web specification data.

How to use W3c Mcp Server?

Install globally via npm install -g @shuji-bonji/w3c-mcp or use directly with npx @shuji-bonji/w3c-mcp. Configure it in Claude Desktop or Cursor by adding a JSON entry with the npx command. Enable debug logging with W3C_MCP_DEBUG=true or W3C_MCP_PERF=true environment variables.

Key features of W3c Mcp Server?

  • Specification discovery with filtering by organization and keyword
  • WebIDL interface definitions for JavaScript APIs
  • CSS property definitions by specification or name
  • HTML element definitions from multiple specs
  • PWA-related specification grouping and dependency info
  • Fast startup (~70ms) and O(1) spec lookups

Use cases of W3c Mcp Server?

  • Find and inspect Service Worker interface definitions
  • Explore all PWA-related specifications in one call
  • Look up CSS Grid layout properties and values
  • Search for storage-related web specifications
  • Retrieve HTML element definitions like video or canvas

FAQ from W3c Mcp Server

What data sources

Comments

Basic information

Category

Other

Transports

stdio

Author

shuji-bonji

Submitted by

shuji narumi

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