# Web Validator by DigestSEO

Validates HTML and CSS against W3C standards, audits SEO metadata, checks broken links, tests JSON-LD markup, and captures responsive screenshots.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 9
- Author: AKzar1el
- License: MIT · policy=link-only · description only; the file stays with the author
- Source: https://github.com/AKzar1el/mcp-web-validator
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/mcp/web-validator-by-digestseo

## What it does

The server provides two distinct integration surfaces: a local npm package executed over stdio and a remote Streamable HTTP endpoint hosted at `https://web-validator-mcp.digestseo.com/mcp`. Local runs require Node.js 22.12.0 or newer.

When operating locally, the package accesses workspace files directly. Tools like `html.local` and `css.local` pass file contents to external W3C Nu and Jigsaw validators, while `seo.metadata` evaluates headings and Open Graph tags locally. The `screenshot.capture` utility fetches a browser into Puppeteer storage during its initial invocation. You can redirect this storage by setting `PUPPETEER_CACHE_DIR`.

The hosted endpoint isolates operations inside a worker environment without local filesystem access. It can audit supplied markup or crawl up to eight sitemap pages while respecting `robots.txt` rules, skipping browser rendering and JavaScript execution altogether.

## Requirements
- Needs: Node.js (commands run via npx)
- Remote server: `https://web-validator-mcp.digestseo.com/mcp`

## Install

### Claude Code (native platform)

1. **Platform CLI: remote server**
```bash
claude mcp add --transport http mcp-web-validator https://web-validator-mcp.digestseo.com/mcp
```

2. **Platform CLI**
```bash
claude mcp add web-validator-by-digestseo -- npx -y mcp-web-validator
```

### Codex

1. **Platform CLI: remote server**
```bash
codex mcp add web-validator-by-digestseo --url https://web-validator-mcp.digestseo.com/mcp
```

2. **Platform CLI**
```bash
codex mcp add web-validator-by-digestseo -- npx -y mcp-web-validator
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "web-validator-by-digestseo": {
            "url": "https://web-validator-mcp.digestseo.com/mcp"
        }
    }
}
```
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "web-validator-by-digestseo": {
            "command": "npx",
            "args": [
                "-y",
                "mcp-web-validator"
            ]
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "web-validator-by-digestseo": {
            "type": "http",
            "url": "https://web-validator-mcp.digestseo.com/mcp"
        }
    }
}
```
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "web-validator-by-digestseo": {
            "type": "stdio",
            "command": "npx",
            "args": [
                "-y",
                "mcp-web-validator"
            ]
        }
    }
}
```

### Gemini CLI

1. **Platform CLI: remote server**
```bash
gemini mcp add -t http web-validator-by-digestseo https://web-validator-mcp.digestseo.com/mcp
```

2. **Platform CLI**
```bash
gemini mcp add web-validator-by-digestseo npx -y mcp-web-validator
```

## When to use it
- validate local HTML and CSS markup against W3C checkers
- detect syntax problems in JSON-LD structured data
- audit Open Graph tags, canonical URLs, and heading hierarchy
- identify broken external links found inside page markup
- generate viewport screenshots across mobile and desktop sizes

## Example prompts
- Run W3C validation on `index.html` and report any syntax errors.
- Audit the SEO meta tags and JSON-LD markup inside `template.html`.
- Take mobile and desktop screenshots of `index.html` and save them to `./screenshots`.

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