Skip to main content

​
Audit categories

squirrelscan organizes its 230+ rules into 21 distinct categories, each focusing on a specific aspect of website health.
Every rule in squirrelscan belongs to one category and has a severity level (error, warning, notice) and rank (1-10) indicating its impact.

​
Category overview

The 21 categories are grouped into logical domains:

Core SEO

Fundamental SEO elements that search engines rely on

Technical SEO

Technical implementation of SEO best practices

E-E-A-T

Expertise, Experience, Authority, and Trustworthiness signals

Keywords

Keyword usage and optimization

Local SEO

Location-based search optimization

​
Core SEO

Core SEO

Fundamental SEO elements that search engines use to understand and rank your content.

​
What it covers

Title tags

  • Title tag presence and length (50-60 characters)
  • Uniqueness across pages
  • Keyword placement
  • Proper formatting
  • Description presence and length (150-160 characters)
  • Uniqueness across pages
  • Compelling copy that encourages clicks
  • Keyword inclusion
  • Canonical tag implementation
  • Self-referencing canonicals
  • Avoiding duplicate content issues
  • og:title, og:description, og:image
  • Proper social media preview setup
  • Image dimensions and formatting

​
Common issues

  • Missing or empty title tags
  • Meta descriptions too short or missing
  • Duplicate titles across multiple pages
  • Missing canonical URLs causing duplicate content
View detailed rules at docs.squirrelscan.com/rules/core-seo

​
Technical SEO

Technical SEO

Technical implementation of SEO best practices for search engine crawlers.

​
What it covers

  • Robots.txt: Proper configuration and accessibility
  • Sitemap.xml: Presence, format, and comprehensiveness
  • Structured data: JSON-LD implementation and validation
  • Hreflang tags: International targeting
  • Pagination: rel=next/prev for paginated content
  • Redirects: Proper 301/302 usage, avoiding chains

​
Common issues

  • Missing or incorrectly configured robots.txt
  • Sitemap not referenced in robots.txt
  • Invalid structured data markup
  • Redirect chains (multiple hops)
  • Missing hreflang for multi-language sites

​
Performance

Performance

Page speed, resource optimization, and loading efficiency.

​
What it covers

​
Speed metrics

  • Page load time
  • Time to first byte (TTFB)
  • First contentful paint (FCP)
  • Largest contentful paint (LCP)

​
Resource optimization

  • Image compression and formats
  • CSS/JS minification
  • Caching headers
  • Resource prioritization

​
Common issues

  • Large unoptimized images
  • Missing cache headers
  • Blocking JavaScript
  • Excessive HTTP requests
  • Slow server response times

​
Security

Security

Security vulnerabilities, HTTPS implementation, and protective headers.

​
What it covers

1

HTTPS implementation

  • SSL/TLS certificate validity
  • HTTPS-only content
  • Mixed content detection
  • HTTP to HTTPS redirects
2

Security headers

  • Content-Security-Policy
  • X-Frame-Options
  • X-Content-Type-Options
  • Strict-Transport-Security
3

Secrets detection

  • API keys in source code
  • Exposed credentials
  • Sensitive data leaks

​
Critical issues

These issues can expose your site to attacks:
  • Missing HTTPS
  • Exposed API keys or tokens
  • Missing security headers
  • Mixed content (HTTP resources on HTTPS pages)

​
Accessibility

Accessibility

WCAG compliance for users with disabilities.

​
What it covers

  • Image alt text: Descriptive alternative text for all images
  • Color contrast: Sufficient contrast ratios (WCAG AA/AAA)
  • Keyboard navigation: Full keyboard accessibility
  • ARIA labels: Proper semantic markup
  • Form labels: Associated labels for all inputs
  • Heading hierarchy: Logical heading structure (H1 → H2 → H3)

​
Common issues

  • Images missing alt text
  • Insufficient color contrast (text vs background)
  • Form inputs without labels
  • Skip navigation links missing
  • Non-semantic HTML usage

​
Content

Content

Content quality, structure, and readability.

​
What it covers

  • H1 tags: Single H1 per page
  • Heading hierarchy: Logical progression (no skipped levels)
  • Paragraph length: Readable chunks
  • List usage: Proper ul/ol formatting

Links

Internal and external link health and optimization.

​
What it covers

Internal links

  • Broken internal links (404 errors)
  • Orphaned pages (no incoming links)
  • Deep link structure
  • Anchor text optimization

External links

  • Broken external links
  • Proper rel attributes (nofollow, noopener)
  • Link destinations
  • Outbound link quality

​
Common issues

❌ Broken internal links
  • Links to deleted pages
  • Incorrect URL paths
  • Missing trailing slashes
❌ External link problems
  • Dead external links
  • Missing rel=“noopener” on target=“_blank”
  • Links to low-quality sites

​
Crawlability

Crawlability

Search engine access and indexation control.

​
What it covers

  • Robots.txt: Crawler directives
  • Sitemap.xml: Page discovery aid
  • Meta robots tags: Per-page indexation control
  • X-Robots-Tag headers: HTTP-level directives
  • URL parameters: Handling of query strings
  • Noindex directives: Proper usage and implications

​
Images

Images

Image optimization, accessibility, and best practices.

​
What it covers

  • Alt text presence and quality
  • Decorative images (empty alt)
  • Image captions
  • File size and compression
  • Modern formats (WebP, AVIF)
  • Responsive images (srcset)
  • Lazy loading
  • Proper dimensions
  • Aspect ratio preservation
  • CDN usage

​
Mobile

Mobile

Mobile-friendliness and responsive design.

​
What it covers

  • Responsive design: Viewport meta tag, fluid layouts
  • Touch targets: Minimum size (44x44px)
  • Font sizes: Legible on mobile (16px minimum)
  • Horizontal scrolling: Avoid horizontal overflow
  • Mobile-friendly navigation: Hamburger menus, touch-friendly

​
Social Media

Social Media

Social sharing optimization and previews.

​
What it covers

  • og:title, og:description, og:image
  • og:type, og:url
  • Image dimensions (1200x630 recommended)

​
URL Structure

URL Structure

Clean, semantic, and SEO-friendly URLs.

​
What it covers

  • Length: Keep URLs under 100 characters
  • Hyphens: Use hyphens (not underscores) for word separation
  • Keywords: Include target keywords
  • Lowercase: Use lowercase letters only
  • Simplicity: Avoid unnecessary parameters and subfolders

​
Good vs Bad URLs

✅ Good URLs
/blog/seo-best-practices
/products/wireless-headphones
/guides/getting-started
❌ Bad URLs
/blog/post?id=12345
/products_wireless_headphones
/p/g/s/Getting_Started

​
Keywords

Keywords

Keyword usage, density, and optimization.

​
What it covers

  • Keyword stuffing: Detecting over-optimization
  • Keyword placement: Title, headings, first paragraph
  • Natural usage: Contextual keyword integration
  • Related terms: Semantic keyword variations

​
E-E-A-T

E-E-A-T

Expertise, Experience, Authority, and Trustworthiness signals for Google.

​
What it covers

  • Author bios: Expert credentials and qualifications
  • Contact information: Easy-to-find contact details
  • About page: Company history and mission
  • External validation: Citations, references, testimonials
  • Content quality: In-depth, accurate, original content

​
User Experience

User Experience

Usability, user flow, and interaction design.

​
What it covers

  • Form validation: Clear error messages
  • Error handling: User-friendly error pages
  • Navigation: Clear menu structure
  • Search functionality: Site search implementation
  • CTA clarity: Clear calls-to-action

​
Schema

Schema

Structured data markup (Schema.org) for rich snippets.

​
What it covers

  • JSON-LD implementation: Proper format and syntax
  • Schema types: Organization, Article, Product, Event, etc.
  • Required properties: Complete schema with all required fields
  • Validation: No errors in structured data

Legal

Legal compliance and required policies.

​
What it covers

  • Privacy policy: GDPR, CCPA compliance
  • Terms of service: User agreements
  • Cookie consent: Cookie notices and opt-in
  • Copyright notices: Proper attribution
  • Disclaimers: Required legal disclaimers

​
Local SEO

Local SEO

Location-based search optimization.

​
What it covers

  • NAP consistency: Name, Address, Phone number
  • Geo metadata: Location tags and structured data
  • Local schema: LocalBusiness markup
  • Google Business Profile: Integration and consistency

​
Video

Video

Video content optimization and accessibility.

​
What it covers

  • VideoObject schema: Structured data for videos
  • Transcripts: Text alternatives
  • Captions: Subtitle availability
  • Thumbnails: Engaging preview images

​
Internationalization

Internationalization

Multi-language and region support.

​
What it covers

  • Hreflang tags: Language and region targeting
  • Language declaration: HTML lang attribute
  • Content localization: Proper translation
  • Regional URLs: Country/language-specific URLs

​
Rule documentation

Each rule has detailed documentation available online:

Rule reference template

https://docs.squirrelscan.com/rules/{category}/{rule-id}
Example: https://docs.squirrelscan.com/rules/links/external-links

​
Next steps

Run an audit

Start auditing websites across all 21 categories

Interpret results

Learn how to prioritize and fix issues

Build docs developers (and LLMs) love

Get started for freeTalk to us