Skip to main content
U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Color Tools

Color Impairment

  • Color Oracle is another desktop application for simulating color impairment on your entire screen.
  • Daltonize is a collection of bookmarklets that simulate the three most common forms of color impairment (protanopia, deuteranopia, and tritanopia) on any web page.
  • 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 UK’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:

  • Accessibility Insights - Browser plugin (Chrome, Edge), Android and Windows applications for automated and guided manual testing for accessibility including WCAG 2.0 and 2.1.
  • AccessLintCI runs accessibility tests in CircleCI builds and comments on GitHub pull requests with new accessibility issues. See more information on how to add this to an 18F site here.
  • axe - Suite of automated accessibility testing tools built around the open source axe-core testing engine/ruleset, by Deque.
  • 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.

18F Accessibility Guide

An official website of the GSA’s Technology Transformation Services

Looking for U.S. government information and services?