mcp-web-validator — HTML validation & technical on-page SEO.
Audit one authorized public webpage, a bounded sitemap-first site, or supplied markup in ChatGPT. Use the open-source local MCP for file-based audits and responsive screenshots.
- Hosted audits
- Page + site
- Site batch
- Up to 8 pages
- Local MCP
- Files + screenshots
- License
- MIT
About
What is mcp-web-validator?
mcp-web-validator is an open-source Model Context Protocol (MCP) server for HTML and CSS validation, technical SEO and accessibility signals, JSON-LD syntax checks, focused link checks, and local responsive screenshots.
The hosted ChatGPT app works with markup you explicitly provide, one authorized public webpage, or a bounded sitemap-first audit of an authorized public site. The separate local MCP works with workspace files and is the only surface that can create responsive screenshots.
The hosted app is read-only. A webpage audit fetches one static HTML document; a site audit first reads same-origin robots.txt and sitemap documents, then audits up to eight eligible same-origin sitemap pages per call. It never discovers pages by following HTML links, runs no site-wide link checker, executes no JavaScript, and cannot access authenticated or private sites. Supplied and fetched HTML is sent to the external Nu HTML Checker; CSS, SEO, and JSON-LD checks run inside the DigestSEO Worker.
Tools
Public ChatGPT capabilities
Read-only tools for supplied markup, focused public webpages, and bounded public-site audits. Submit only markup and public URLs you are authorized to share or inspect.
validate_html Sends supplied HTML to the external Nu HTML Checker and returns capped diagnostics.
audit_public_webpage Fetches one authorized public static HTML page for Nu HTML validation plus local SEO and JSON-LD checks. Optional link checking is capped at 20 links.
audit_public_site Audits up to eight authorized, same-origin sitemap pages per call after reading robots.txt. It does not follow HTML links or run site-wide link checks.
validate_css Parses supplied CSS inside the hosted Worker and reports syntax errors.
audit_seo_metadata Audits supplied HTML for titles, descriptions, headings, image alt text, canonical tags, viewport tags, and Open Graph metadata.
check_broken_links Checks up to 20 eligible public links found in supplied HTML without following redirects.
validate_schema_markup Checks JSON-LD blocks in supplied HTML for JSON syntax errors, not Schema.org vocabulary semantics.
generate_validation_report Combines Nu HTML validation with CSS, SEO, and JSON-LD checks for supplied markup; base_url resolves links but does not fetch a page.
ChatGPT app
Use it in ChatGPT without local filesystem access
Install Web Validator by DigestSEO from the ChatGPT App Directory once it is available in your region. Provide HTML or CSS, audit one authorized public webpage, or audit a bounded sitemap-first batch of up to eight same-origin public pages. The hosted app respects applicable robots.txt rules for site audits; it does not follow HTML links, run site-wide link checks, render JavaScript, fetch linked CSS, sign in, or create screenshots. See the privacy policy for the data flow or visit support.
Setup
Configure the local MCP in your IDE
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
npm install -g mcp-web-validator
# Or execute on the fly with npx:
npx -y mcp-web-validatorStar the repo and improve your local AI coding loop today.
MIT licensed. HTML validation and technical SEO audits.