validatehtml MCP server

Q: How do I add validatehtml MCP to Claude Code?

Run `claude mcp add --env VALIDATEHTML_API_KEY= validatehtml-cli -- npx -y validatehtml` in your terminal. Add `--scope user` to make it available in every project.

Q: How do I add validatehtml MCP to Cursor?

Open `~/.cursor/mcp.json` and add the server under `mcpServers`, using the Cursor config shown in the install section above.

✓ VerifiedCommit Nov 10, 2026

theodcrx/validatehtml-cli · javascript · MIT

Validates HTML, CSS, JSON, XML, and WCAG accessibility compliance for local files or live URLs.

Also known as theodcrx/validatehtml-cli, validatehtml-cli

stdio Developer Tools

Install GitHub ↗

Stars: 0
Tools: —
Downloads, 30 days: —
Latest version: 0.1.0
Last commit: Nov 10, 2026
License: MIT

What is validatehtml MCP?

validatehtml validates HTML, CSS, JSON, XML, and WCAG accessibility compliance for local files or live URLs.

Summary generated from the project's README

About validatehtml MCP server

Checking code syntax and accessibility compliance from within an AI coding agent is what validatehtml enables. Developers can use this tool to verify HTML, CSS, JSON, and XML files, or to test live URLs and local development servers. It works through various MCP clients like Claude Code, Cursor, Windsurf, and VS Code by running via npx.

The server provides specific tools including validate_code, validate_file, and validate_url to handle different validation tasks. For more comprehensive checks, the audit_page tool examines meta tags, Open Graph data, and page weight, though this specific function requires a VALIDATEHTML_API_KEY. While basic validation requires no account, the audit feature is subject to monthly call limits based on your plan.

Files sent for validation, such as .html, .css, .json, .xml, or .svg, are processed in memory and not stored. The system supports files up to 1 MB and can read from standard input. It returns specific exit codes to integrate easily into automated build scripts or terminal workflows.

What you can do with it

1Automate build script validationIntegrate validation into a CI/CD pipeline by using exit codes to signal success or failure.

Written from the project's README. Every use case is checked against a quote from it.

How to install validatehtml MCP

Formats verified 10 Nov 2026

Claude CodeCursorVS CodeClaude DesktopCodexGemini CLI

$ claude mcp add --env VALIDATEHTML_API_KEY=<YOUR_VALIDATEHTML_API_KEY> validatehtml-cli -- npx -y validatehtml

~/.cursor/mcp.json

{
  "mcpServers": {
    "validatehtml-cli": {
      "command": "npx",
      "args": [
        "-y",
        "validatehtml"
      ],
      "env": {
        "VALIDATEHTML_API_KEY": "<YOUR_VALIDATEHTML_API_KEY>"
      }
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "validatehtml-cli": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "validatehtml"
      ],
      "env": {
        "VALIDATEHTML_API_KEY": "<YOUR_VALIDATEHTML_API_KEY>"
      }
    }
  }
}

claude_desktop_config.json

{
  "mcpServers": {
    "validatehtml-cli": {
      "command": "npx",
      "args": [
        "-y",
        "validatehtml"
      ],
      "env": {
        "VALIDATEHTML_API_KEY": "<YOUR_VALIDATEHTML_API_KEY>"
      }
    }
  }
}

~/.codex/config.toml

[mcp_servers.validatehtml-cli]
command = "npx"
args = ["-y", "validatehtml"]

[mcp_servers.validatehtml-cli.env]
VALIDATEHTML_API_KEY = "<YOUR_VALIDATEHTML_API_KEY>"

~/.gemini/settings.json

{
  "mcpServers": {
    "validatehtml-cli": {
      "command": "npx",
      "args": [
        "-y",
        "validatehtml"
      ],
      "env": {
        "VALIDATEHTML_API_KEY": "<YOUR_VALIDATEHTML_API_KEY>"
      }
    }
  }
}

Set 1 environment variable before starting the server (below).Setup guides:Claude Code Cursor VS Code Claude Desktop

Configuration

VALIDATEHTML_API_KEYSecret
Optional. Only audit_page needs it. 100 free calls a month.

Name	Description
VALIDATEHTML_API_KEY	Optional. Only audit_page needs it. 100 free calls a month.	Secret

Automated checks

Ran Nov 14, 2026Full report →

100/100

Passed our automated checks. That is not a security audit: read the code and give the server the narrowest access it needs. How checks work

Show this score in your README

Source repository linked and reachabletheodcrx/validatehtml-cli is public and reachablegithub.com/theodcrx/validatehtml-cli ↗Pass
Package names this repository as its sourcevalidatehtml names theodcrx/validatehtml-cli as sourcenpmjs.com/package/validatehtml ↗Pass
Build provenance (Sigstore attestation)No build attestation published for this releaseNot checked
Open source license (OSI)MITspdx.org/licenses/MIT.html ↗Pass
Commit or release in the last yearLast commit or release 2026-11-10github.com/theodcrx/validatehtml-cli ↗Pass
OpenSSF ScorecardNot checked
Package name not close to a popular packageNo popular package one edit away from validatehtmlPass
No critical advisory in the package or its dependencies99 resolved dependencies checked; no critical advisoryosv.dev ↗Pass
No hidden instructions to the model0 tool descriptions and the README read; no override phrases, credential paths or hidden charactersPass
Destructive tools are labelledNot checked
Remote endpoint answers the MCP handshakeNot checked

README

View on GitHub

validatehtml

Validate HTML, CSS, JSON, XML and accessibility from your terminal or your AI coding agent. Errors are spec violations, warnings are best practices, and modern valid code stays clean.

npx validatehtml index.html
npx validatehtml https://example.com
npx validatehtml http://localhost:3000 --type accessibility

No account and no key. Exit code 0 when it passes, 1 when it fails, 2 when it could not run, so it fits in a script or a build.

For AI coding agents (MCP)

Claude Code:

claude mcp add validatehtml -- npx -y validatehtml mcp

Cursor, Windsurf, VS Code and any other MCP client:

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

Tool	What it does	Key
`validate_code`	Checks HTML, CSS, JSON, XML, or HTML for WCAG issues	No
`validate_file`	The same on a local file, without reading it into the conversation	No
`validate_url`	Checks a live page, including a dev server on localhost	No
`audit_page`	Every check on one deployed page: HTML, accessibility, meta tags, Open Graph, page weight	Yes
`site_scan_link`	A link for you to scan a whole site in your browser	No

Agent skill

skills/validatehtml/SKILL.md tells an agent when to validate and how to read the result (fix errors, report warnings, never claim WCAG compliance). Copy the folder into .claude/skills/ (or your agent's skills folder) next to the MCP server.

Command line

validatehtml <file|url|->  [--type html|css|json|xml|accessibility]
                           [--audit] [--fail-on error|warning] [--format text|json]
validatehtml mcp

- reads standard input. --audit needs a key.

Key

--audit and audit_page use VALIDATEHTML_API_KEY. Create one at https://validatehtml.com/dashboard. A free account includes 100 calls a month; larger allowances are on the pricing page.

What leaves your machine

The code or file you ask to check is sent to validatehtml.com, checked in memory and not stored. A page on localhost is read on your machine and sent the same way. Only .html, .htm, .css, .json, .xml and .svg files can be read, up to 1 MB. Each call also counts the tool used and the package version, never the content.

Licence

MIT for this client. The licence does not cover the ValidateHTML name.

Read full README

validatehtml MCP questions

How do I add validatehtml MCP to Claude Code?

Run claude mcp add --env VALIDATEHTML_API_KEY=<YOUR_VALIDATEHTML_API_KEY> validatehtml-cli -- npx -y validatehtml in your terminal. Add --scope user to make it available in every project.

How do I add validatehtml MCP to Cursor?

Open ~/.cursor/mcp.json and add the server under mcpServers, using the Cursor config shown in the install section above.

What files can be validated?

The tool can read .html, .htm, .css, .json, .xml, and .svg files up to 1 MB.

Is my code stored on your servers?

Code is checked in memory and is not stored.

Facts

Nov 14, 2026

Stars: 0
Downloads, 30 days: —
Latest version: 0.1.0
Last commit: Nov 10, 2026
License: MIT
Transport: stdio
Package: validatehtml

theodcrx ↗

Community publisher

Published by an independent maintainer.

Alternatives

Works with

Claude Code Cursor VS Code Claude Desktop Codex Gemini CLI Windsurf Devin

Badge for your README

Show your HostedMCP checks score. The badge links readers to install instructions for every client.

[![HostedMCP checks](https://api.hostedmcp.org/v1/badge/server/theodcrx/validatehtml-cli.svg)](https://hostedmcp.org/servers/theodcrx/validatehtml-cli/checks)

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Before you install

Servers run with the permissions you give them. Use the narrowest token or database role that does the job.

About validatehtml MCP server

What you can do with it

1Automate build script validationIntegrate validation into a CI/CD pipeline by using exit codes to signal success or failure.

Written from the project's README. Every use case is checked against a quote from it.

{ "mcpServers": { "validatehtml-cli": { "command": "npx", "args": [ "-y", "validatehtml" ], "env": { "VALIDATEHTML_API_KEY": "<YOUR_VALIDATEHTML_API_KEY>" } } } }

{ "servers": { "validatehtml-cli": { "type": "stdio", "command": "npx", "args": [ "-y", "validatehtml" ], "env": { "VALIDATEHTML_API_KEY": "<YOUR_VALIDATEHTML_API_KEY>" } } } }

{ "mcpServers": { "validatehtml-cli": { "command": "npx", "args": [ "-y", "validatehtml" ], "env": { "VALIDATEHTML_API_KEY": "<YOUR_VALIDATEHTML_API_KEY>" } } } }

Name

Description

VALIDATEHTML_API_KEY

Optional. Only audit_page needs it. 100 free calls a month.

Secret

Tool

What it does

Key

validate_code

Checks HTML, CSS, JSON, XML, or HTML for WCAG issues

validate_file

The same on a local file, without reading it into the conversation

validate_url

Checks a live page, including a dev server on localhost

audit_page

Every check on one deployed page: HTML, accessibility, meta tags, Open Graph, page weight

Yes

site_scan_link

A link for you to scan a whole site in your browser

validatehtml MCP questions

How do I add validatehtml MCP to Claude Code?

Run claude mcp add --env VALIDATEHTML_API_KEY=<YOUR_VALIDATEHTML_API_KEY> validatehtml-cli -- npx -y validatehtml in your terminal. Add --scope user to make it available in every project.

How do I add validatehtml MCP to Cursor?

Open ~/.cursor/mcp.json and add the server under mcpServers, using the Cursor config shown in the install section above.

What files can be validated?

The tool can read .html, .htm, .css, .json, .xml, and .svg files up to 1 MB.

Is my code stored on your servers?

Code is checked in memory and is not stored.

validatehtml MCP server

What is validatehtml MCP?

About validatehtml MCP server

What you can do with it

How to install validatehtml MCP

Install validatehtml MCP in Claude Code

Install validatehtml MCP in Cursor

Install validatehtml MCP in VS Code

Install validatehtml MCP in Claude Desktop

Install validatehtml MCP in Codex

Install validatehtml MCP in Gemini CLI

Configuration

Automated checks

README

validatehtml

For AI coding agents (MCP)

Agent skill

Command line

Key

What leaves your machine

Licence

validatehtml MCP questions

validatehtml MCP server

What is validatehtml MCP?

About validatehtml MCP server

What you can do with it

How to install validatehtml MCP

Install validatehtml MCP in Claude Code

Install validatehtml MCP in Cursor

Install validatehtml MCP in VS Code

Install validatehtml MCP in Claude Desktop

Install validatehtml MCP in Codex

Install validatehtml MCP in Gemini CLI

Configuration

Automated checks

README

validatehtml

For AI coding agents (MCP)

Agent skill

Command line

Key

What leaves your machine

Licence

validatehtml MCP questions