Compare software

SiteOne CrawlerTotal Validator
Free

Free and open source.

 Freemium

A Basic edition is offered alongside paid Pro and CI editions.

Windows, macOS, Linux, Command line Browser extension
  • Broad audit covering SEO, security, accessibility and performance
  • Both a desktop GUI and a scriptable CLI
  • Accessibility tests for WCAG 2.2, Section 508 and ARIA
  • HTML, CSS, link and spelling checks in one tool
  • The large number of CLI options takes time to learn
  • Crawling large sites can put load on the target server
  • Advanced features are split across paid editions
  • Supported operating systems are not stated on the homepage
Downloadable app Downloadable app, Browser extension
Open source Closed source
License not stated License not stated
No account needed Not stated if an account is needed
Not stated if it works offline Not stated if it works offline

Checked September 24, 2026

Checked October 2, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.