Tools
An updated version of this document is being created at: /wiki/spaces/ACCESSIBIL/pages/2710568967
There are many tools that are available online to test a website for WCAG 2.0 conformance. These are just a few.
Dashboards
Siteimprove
Comprehensive a11y-checker, spell-checker, link-checker and more, all rolled into an enterprise-grade dashboard for managing content and fixes.
Pa11y - Open Source a11y Dashboard
A hosted Open Source a11y-checker, able to run on timed intervals and produce reports. Supports multiple sites and URLs (by creating an entry for each URL).
Toolbars, Plugins & Bookmarklets
Lighthouse
https://developers.google.com/web/tools/lighthouse/
Easily audit pages that require authentication, and read your reports in a user-friendly format. It has a Chrome and Firefox plugin. It also be run as a node package or on the command line.
aXe
https://www.deque.com/products/axe/
Free, open-source accessibility testing tool that runs in your web browser (Firefox and Chrome).
WAVE Toolbar
https://wave.webaim.org/toolbar/
Chrome extension and Firefox plugin. In addition to flagging errors and alerts, it also provides nifty tools like "Text only" and "Outline" modes.
HTML_Codesniffer
http://squizlabs.github.io/HTML_CodeSniffer/
JS bookmarklet that works with all browsers. Provides clear results with links to appropriate WCAG 2.0 documentation and suggested fixes.
tota11y Accessibility Visualization Toolkit
http://khan.github.io/tota11y/
Can be used and installed as a bookmarklet OR it can be inserted directly into a webpage using a simple bit of Javascript. It's Open Source, licensed under MIT and forkable on GitHub.
Contrast Checkers
WebAIM Color Contrast Checker
http://webaim.org/resources/contrastchecker/
Snook's Color Contrast Check
http://www.snook.ca/technical/colour_contrast/colour.html
Contrast Ratio
https://leaverou.github.io/contrast-ratio/
Accessibility Color Wheel
http://gmazzocato.altervista.org/colorwheel/wheel.php