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