Squirrelscan MCP Server

squirrelscan

The website QA tool for your coding agent

squirrelscan is an Open Source cli tool that audits websites for SEO, performance, security, accessibility, agent experience and other issues, and gives your coding agent exact fixes. Run it from the CLI, inside your coding agent, in the cloud, or over MCP.

Combine your coding agent with a deterministic and extensible audit tool.

A real run on a tiny test site, with the released CLI (signed out, so free) and Claude Code. We cut the two minutes the agent spent working, because nobody wants to watch an agent think.

Features

• 300+ Rules, 22 Categories - Comprehensive coverage across SEO, accessibility, performance, and security
• Fast crawler - Highly optimized memory efficient crawler
• Agent Experience - Audit agent experience to assist agents in using your site
• Security Audit - Detect phishing kits, leaked credentials, and more
• Smart Incremental Crawling - ETag, Last-Modified, content hashing. Resume from checkpoints.
• Developer-First CLI - Single binary, zero dependencies, shell completions, self-update
• Crawl History & Changes - Track site evolution, compare crawls, spot regressions
• Multiple Output Formats - Console, JSON, HTML, Markdown, Text, LLM, XML
• MCP Connection - Connect your agent to local or cloud MCP to run audits, fixes, etc.

Rule categories

Ordered by how much a failure usually costs you, not by how many rules each one has.

Total: 300+ rules across 22 categories

See the rules reference for full details.

CLI

Installation

Paste into your coding agent (Claude Code, Codex, Cursor, opencode and friends):

Fetch and follow the setup instructions for squirrelscan at https://docs.squirrelscan.com/agent-setup/prompt.md

Your agent installs the CLI, connects MCP and runs a first audit. You can read exactly what it will follow first.

macOS / Linux:

curl -fsSL https://install.squirrelscan.com | bash

Windows:

iwr -useb https://install.squirrelscan.com/install.ps1 | iex

Homebrew (macOS):

brew install --cask squirrelscan/tap/squirrel

The cask installs a launcher that runs the regular installer on first use. The CLI then updates itself with squirrel self update; brew upgrade leaves it alone.

npm (all platforms):

npm install -g squirrelscan

npx (run without installing):

npx squirrelscan audit example.com

Quick start

# Audit a website
squirrel audit example.com

# Generate HTML report
squirrel audit example.com -f html -o report.html

# Pipe to Claude for AI analysis
squirrel audit example.com --format llm | claude

# Quick audit for a fast first look (other levels: surface, full)
squirrel audit example.com --level quick

# run only agent experience and performance rules
squirrel audit example.com --rule-include ax,performance

# login for cloud audits and cloud rendering
squirrel auth login

Reports

Category scores for SEO, performance, security and Agent Experience (AX). Publish reports to the web to share with team members or coding agents (fix instructions are embedded)

see an example report

Add to your coding agent

squirrelscan ships as an MCP server (hosted at mcp.squirrelscan.com), skills (autonomous audit + fix workflows), and a plugin for Claude Code and Cursor. Cursor installs in one click from the badge above; the rest are a single copy-paste.

Cursor

Click the Add to Cursor badge above, or add it manually to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "squirrelscan": { "url": "https://mcp.squirrelscan.com/mcp" }
  }
}

Skills: squirrel skills install

Claude Code

Install the plugin (bundles skills + the MCP server):

/plugin marketplace add squirrelscan/skills
/plugin install squirrelscan@squirrelscan

Or add just the MCP server:

claude mcp add --transport http squirrelscan https://mcp.squirrelscan.com/mcp

OpenAI Codex

Add the server to ~/.codex/config.toml:

[mcp_servers.squirrelscan]
url = "https://mcp.squirrelscan.com/mcp"

Codex reads Agent Skills from ~/.agents/skills, so skills work too: squirrel skills install

opencode

Add the server to opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "squirrelscan": {
      "type": "remote",
      "url": "https://mcp.squirrelscan.com/mcp",
      "enabled": true
    }
  }
}

Any MCP client

squirrelscan is in the MCP Registry as com.squirrelscan/squirrelscan. Point any client at the remote server:

https://mcp.squirrelscan.com/mcp

Authentication is per-user OAuth (or pass a squirrelscan API key as a Bearer token). Skills follow the Agent Skills standard: squirrel skills install puts them in ~/.agents/skills/ and ~/.claude/skills/.

Skills

Two skills drive agent workflows. They live in squirrelscan/skills, along with the Claude Code, Cursor and Agent Plugins packages that bundle them with the MCP server. squirrel skills install downloads and verifies them itself, and from v0.0.99 squirrel's auto-update keeps them current. Installs made earlier with npx skills are taken over.

• squirrelscan - operating the CLI: install, login, keys, credits, running audits, publishing reports, the entity map, MCP setup, config, troubleshooting.
• audit-website - the full fix loop: audit, map issues to source files, fix in batches, re-audit until the site scores well.

squirrel skills install

Then, in your agent:

Use the audit-website skill to audit this site and fix all issues but only crawl 10 pages

Output formats

Source and development

The complete local CLI, crawler, audit engine, rules, report generators, CLI-facing cloud clients, and documentation site are open source in this repository. The hosted API, website, dashboard, and cloud worker implementations are separate private services.

Prerequisites: Bun 1.4.0 and Git.

git clone https://github.com/squirrelscan/squirrelscan.git
cd squirrelscan
bun install --frozen-lockfile
bun run dev -- audit https://example.com --max-pages 10

Run the same checks used in pull requests:

bun run format:check
bun run lint
bun run typecheck
bun test
bun run build
bun run docs:check
bun run docs:build

See CONTRIBUTING.md before opening a pull request. Contributions require a Developer Certificate of Origin sign-off (git commit -s).

Telemetry

Telemetry is enabled by default and is deliberately minimal: event name, CLI version, a random install ID, and bounded error categories. It does not send credentials, URLs, report contents, or raw error messages, and telemetry requests are never authenticated.

Disable it permanently with:

squirrel self settings set telemetry false

Or disable all telemetry and install registration for any invocation by defining NO_TELEMETRY. Any defined value works, including an empty value, 0, or false:

NO_TELEMETRY=1 squirrel audit https://example.com

Links

• Website
• Documentation
• Coding agent integration
• Share feedback
• Bugs, issues and feature requests
• Twitter/X

If squirrelscan caught something your agent missed, a star on GitHub helps other developers find it.

License

The CLI and the repository contents are licensed under the MIT License. squirrelscan names and logos are covered by TRADEMARKS.md.