Open source · MIT licensed

mcp-web-validator — technical on-page SEO & W3C validator.

Empower your AI coding assistants to audit markup syntax, SEO metadata, JSON-LD schemas, link integrity, and capture responsive screenshots locally in your workspace.

View on GitHub Setup Configuration

MCP tools: 8
Audit layers: 5
Setup time: ~1 min
License: MIT

About

What is mcp-web-validator?

mcp-web-validator is an open-source Model Context Protocol (MCP) server that empowers AI assistants to validate markup syntax (W3C HTML & CSS), inspect Schema.org graphs, check links integrity, and capture layout screenshots in multiple viewports.

AI agents generate a large amount of code, but they lack a loop to verify if it is valid or responsive. This server bridges that gap, giving your local model tools to automatically test and repair layout code as it writes it.

It runs entirely inside your local terminal or IDE. It fits perfectly into your technical SEO pipeline, complementing your visibility metrics from mcp-geo by ensuring the foundational structure of your site remains robust and readable for search engines and AI web crawlers.

Tools

Developer capabilities

Eight specialized tools you can call from Claude Desktop, Cursor, or any other MCP-enabled editor.

01 validate_local_html

Validates local HTML syntax and structure using the official W3C Nu HTML Checker.

02 validate_local_css

Checks local CSS syntax and compliance using the W3C Jigsaw CSS Validation engine.

03 audit_seo_metadata

Runs local technical SEO audits for titles, descriptions, headings, images, and Open Graph tags.

04 check_broken_links

Scans HTML files to detect broken internal or external hyperlinks and return status codes.

05 validate_schema_markup

Identifies and validates JSON-LD structured schema blocks for syntax errors.

06 generate_validation_report

Runs all validators and builds a unified PageSpeed-inspired markdown report card.

07 capture_screenshots

Launches local headless Puppeteer to capture layout screenshots at multiple responsive viewports.

Setup

Configure your IDE in 30 seconds

Claude Desktop

Add this to your claude_desktop_config.json:

{
  "mcpServers": {
    "mcp-web-validator": {
      "command": "npx",
      "args": ["-y", "mcp-web-validator"]
    }
  }
}

Cursor

Navigate to Settings > Features > MCP and add:

Name: mcp-web-validator
Type: command
Command: npx -y mcp-web-validator

CLI Execution

Run audits directly from the console

~/mcp-web-validator

npm install -g mcp-web-validator
# Or execute on the fly with npx:
npx -y mcp-web-validator

Star the repo and improve your local AI coding loop today.

MIT licensed. Full W3C compliance & technical SEO audits.

View on GitHub