How about a linter package for Atom that checks for accessibility compliance, with the choices being ARIA, WCAG A, WCAG AA, WCAG AAA, and Section 508? There are plenty of online linters, some of which may have an API. Some command-line-based utilities are…
https://github.com/DuaneOBrien/A11YLint-Brackets using https://github.com/adobe/brackets
https://github.com/yargalot/AccessSniff using https://github.com/squizlabs/HTML_CodeSniffer
ruby gems based:
For more information on accessibility, here’s a slough of resources. Look at the Online Tools and Development Tools sections.