Feature checklists rarely decide anything. What decides it is the pricing metric, who has to write the tests, and which limitation you can live with.
Entry price
From $0.04 per page (API, indicative)
Free tierQuote on request
Quote onlyWhat drives the bill
The metric that actually scales your invoice.
Free for interactive use; the API is priced per page for bulk scanning.
Enterprise annual contracts priced by pages crawled and modules.
Free tier
Browser extension and single-page online checker are free.
Free browser extension for single-page checks.
Open source
Self-hostable
No-code authoring
Languages
Platforms
Fits teams
Adoption
Widely used
WebAIM (Utah State University) · since 2001
Widely used
Siteimprove · since 2003
Strengths
Limitations
Best for
Designers and developers learning accessibility, and quick manual spot checks.
Universities, government and large content organisations with legal accessibility obligations.
Pricing last reviewed August 2026 and is indicative only — confirm on each vendor’s own page.