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Accessibility Guide

Practices and tools for making products and services accessible to everyone.


Color tools

Color impairment

  • Color Oracle is another desktop application for simulating color impairment on your entire screen
  • colourblind is another simulation tool similar to Daltonize, but with more options (protanopia, protanomaly, deuteranopia, deuteranomaly, tritanopia, tritanomaly, achromatopsia, and achromatomaly) in a single bookmarklet
  • postcss-colorblind is a CSS build tool that modifies colors in your CSS to simulate four common impairment groups

Accessibility review tools

These tools can be used to test sites for Section 508 and WCAG compliance in browser:

Autocomplete widgets

These JavaScript widgets produce HTML with ARIA autocomplete attributes:

Automated testing

Automated testing tools can help you find some of the more common accessibility mistakes quickly. However, no automated tool can detect all accessibility issues. A recent experiment by the U.K.’s Government Digital Service found that the best automated tools only caught about 40 percent of the errors on a test site; some of the most popular tools caught less than 20 percent. Whatever automated tool you use, be sure to also do manual testing. These tools can be used in automated tests and with continuous integration tools to help you ensure that your sites remain accessible throughout the development process:

  • a11y is a Node-based accessibility auditing with both command-line and JavaScript APIs
  • AccessLintCI runs accessibility tests in CircleCI builds and comments on GitHub pull requests with new accessibility issues
  • pa11y is like a11y, but consists of a larger suite of tools, including command-line and JavaScript APIs, a web service, and a dashboard for monitoring accessibility reports across multiple sites
  • ra11y is a Ruby-based accessibility testing tool tuned for use with Jekyll and static sites
  • webalin is a Python-based 508 compliance linter for HTML

There are many other npm packages tagged wcag and a11y.

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