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.

Features

• 301 Rules, 21 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.

Category	Rules	What it covers
Crawlability	20	Whether search engines and agents can reach and index you at all: robots.txt, sitemap validity and coverage, indexability conflicts, redirect and canonical chains, soft 404s
Core SEO	14	The per-page fundamentals: title, meta description, H1, canonical, charset, doctype, robots meta, Open Graph and Twitter cards, plus canonical form drift across the site
Agent Experience	17	How ready you are for AI agents to read, discover and act on the site: whether GPTBot and Claude-User get the same content a browser does, AGENTS.md, llms.txt, Markdown responses, API and MCP discovery, licensing and noai signals, pay-per-crawl, response token weight
Site Integrity	9	Signs the site has been compromised: injected doorway pages, phishing kit signatures, obfuscated scripts, brand impersonation, cloaking, known-malicious URLs
Security	20	Transport and header hygiene: HTTPS and HSTS, CSP, cookie flags, mixed content, subresource integrity, leaked secrets, tokens in web storage, unprotected and downgraded forms, open GraphQL introspection and mutations over GET
Links	15	Internal and external link health: broken and dead links, redirect chains, anchor-text quality, orphan and dead-end pages, pages linked only from sitewide chrome, HTTPS downgrades
Content	23	Text quality and honesty: duplicate titles and descriptions, title-template consistency, readability, word count, freshness, heading hierarchy, keyword stuffing, hidden text, placeholder media and contact details, encoding damage
Performance	30	Core Web Vitals and delivery: LCP, CLS and INP hints, TTFB, compression, caching, render-blocking resources, DOM size, font delivery, legacy and unminified JS/CSS
Images	15	Alt text, modern formats, responsive srcset, intrinsic dimensions and aspect-ratio mismatches, lazy loading above versus below the fold, file weight
Structured Data	25	JSON-LD validity and rich-result eligibility for Article, Product, FAQ, Review, Breadcrumb, Organization, LocalBusiness, Video and site search, plus thirteen site-wide checks on the entity map: whether the site declares one identity for itself or a new one on every page, and rating markup that is not about the page it sits on
Accessibility	61	WCAG coverage: ARIA roles and names, form labels and autocomplete tokens, colour contrast, heading order, landmarks, tables and lists, focus visibility, touch targets, captions
Mobile	6	Viewport configuration, tap-target size, legible font sizes, horizontal scroll, blocked zoom, intrusive interstitials
Social Media	5	Open Graph and Twitter Card completeness, image dimensions, canonical URL match, social profile links, site-chrome assets that disagree across pages
URL Structure	9	Length, casing, hyphenation, stop words, query parameters, special characters, trailing-slash consistency, site-wide convention consistency
E-E-A-T	15	Experience, expertise, authority and trust signals: author bylines and credentials, about and contact pages, citations, editorial policy, disclaimers, YMYL detection
Legal Compliance	4	Privacy policy, terms of service, real cookie-consent machinery, subprocessor disclosure
Internationalization	2	hreflang correctness and the document language declaration
Local SEO	3	NAP (name, address, phone) consistency across every crawled page, geo metadata, service-area businesses
Video	3	VideoObject markup, captions and accessibility, thumbnails
Analytics	2	Google Tag Manager presence and consent-mode wiring
Blocking	3	Content, links and trackers that ad blockers and privacy filters strip for a large share of your visitors

Total: 301 rules across 21 categories

See the rules reference for full details.

CLI

Installation

macOS / Linux:

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

Windows:

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

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

Format	Flag	Use Case
Console	(default)	Human-readable terminal output
JSON	-f json	CI/CD, programmatic processing
HTML	-f html	Visual reports for sharing
Markdown	-f markdown	Documentation, GitHub
Text	-f text	Clean output for piping to LLMs
LLM	-f llm	LLM optimized output
XML	-f xml	XML output

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

License

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