Pa11y is an automated accessibility testing tool. It runs HTML CodeSniffer from the command line for programmatic accessibility reporting.
Related projects
The Node.js-based Pa11y command-line tool is the core tool in the suite. It uses a PhantomJS instance to browse a supplied webpage, and then runs Squizlabs' HTML_Codesniffer on that webpage, returning any accessibility errors it finds.
There is also a separate Pa11y Dashboard project for running a series of tests and graphing errors over time, a CI tool, and a webservice.
Documentation