Polypane
Browser for testing responsive, accessible websites
IBM Equal Access Accessibility Checker
Automated accessibility checking in the browser and in CI
Colour Contrast Analyser
Desktop colour contrast checker for WCAG conformance
ANDI
Accessible Name & Description Inspector bookmarklet
Asqatasun
Open source web accessibility analyser (RGAA, WCAG)
Sa11y
Accessibility quality assurance assistant for content authors