You can add these free tools to your web browser to start checking pages for accessibility.
Accessible Name and Description Inspector - ANDI is a free tool to test web content for accessibility provided by the U.S. Social Security Administration. It is available for Chrome, Edge, FireFox, Internet Explorer, and Safari.
aXe - Test web page accessibility in Chrome
ColorZilla - Test color contrast in Chrome
HTML5 Outliner - Generate a page outline to identify headings and sections
Tenon Check - Test web page accessibility in Chrome
SiteImprove - Test web page accessibility in Chrome
WAVE Evaluation Tool - Test web page accessibility in Chrome
WAVE Accessibility Extension - Test web page accessibility in FireFox
Web Developer for FireFox - Test web page accessibility in FireFox