To echo mkozlows, definitely check out axe-core. They recently open-sourced the tool and it's chock full of great a11y testing. At Khan Academy we use Chrome's

To echo mkozlows, definitely check out axe-core. They recently open-sourced the tool and it's chock full of great a11y testing. At Khan Academy we use Chrome's Accessibility Developer Tools (https://github.com/GoogleChrome/accessibility-developer-tools/ https://github.com/GoogleChrome/accessibility-developer-tool...) as part of our testing infrastructure. A few of us also have the browser extension to do some manual testing, which is what tota11y is for. tota11y uses Accessibility Developer Tools internally.