What is ASLint?

ASLint is an accessibility validation utility. It is designed and created by Cezary Tomczyk of eSSENTIAL Accessibility.

Why was ASLint created?

  • To work with Single Page Applications.
  • To provide a simple explanation of each problem.
  • To show the business impact so you can focus on which problem has to be fixed first.
  • To easily plug-in to automated tests.


  • Verify the accessibility of your content in real-time, including Single Page Applications.
  • Review the results and determine the impact on the business.
  • Does not send content or data externally, so it can be used for internal-only purposes.
  • Tests can be run asynchronously (without blocking the UI) or synchronously.
  • Provides a code snippet to add to a build pipeline (e.g. for automated tests) or the developer console, or can run as a bookmarklet.
  • Easy locate issues on the page from the results using element highlighter or XPath
  • Color contrast recommendations
  • Provides a checklist for things that can’t be tested automatically.
  • Provides WCAG 2.0 level A, AA, AAA, and Section 508 tests.
  • Provides our proprietary eSSENTIAL best practice tests covering issues that aren’t included in Section 508 or WCAG.
  • Provides the option to emulate High Contrast Mode (experimental).
  • Every report contains:
    • an explanation of the issue,
    • what’s causing the issue,
    • options to locate the visible element or by XPath,
    • user impact,
    • and links to external resources (where available) to get more details about the issue.

Get in touch

That’s not the end and ASLint will evolve.

Questions? Nice things to say? Criticisms? Contact us directly.