By Kate Kalcevich — Accessibility testing is critical to ensure that what you build will work for all users. This includes people with disabilities and people with temporary and situational limitations. For example, both having low vision or being outdoors on a sunny day makes color contrast more important.
Layering accessibility testing means using a variety of tools and approaches at different stages in the product lifecycle. It helps you to catch accessibility issues early—when it’s easier to fix them.
Layer one: User research
Teams should include people with disabilities in user research to understand their needs. Ensure the questions you use to screen research participants ask about their accessibility needs. If you can’t find participants this way, reach out to disability organizations or vendors that do accessibility research.
Layer two: Automated tools
Automated testing tools can find anywhere from 30% to 60% of accessibility issues. Here are some free tools to choose from:
- Browser extensions like WAVE or Accessibility Insights let you test individual web pages.
- Native app tools include Accessibility Scanner for Android and Accessibility Inspector for iOS.
- Tools like axe Core or Pa11y can be added to continuous integration testing.
- Plugins like Sa11y or Editoria11y for content management systems find accessibility issues during content editing.
- Crawlers like Purple Hats check all pages in a staging or production environment.
Layer three: Manual QA
You can integrate basic accessibility QA into your existing process. Keyboard access is an accessibility issue that isn’t caught by most automated tools. It’s also a big barrier for many assistive technology users. Simply stop using the mouse during your regular QA testing to find elements that aren’t keyboard‑accessible.
Other ways to do manual accessibility QA include:
- Set the browser zoom to 200% while doing QA to check for content reflow. Content shouldn’t overlap or be obscured.
- Use dark mode in your OS and see if your site works well for people with light sensitivity.
- Check that ARIA announcements work as expected by using a screen reader to listen to them.
Layer four: Testing with users
Large organizations should budget for hiring assistive technology users to test their key task flows. Assistive technologies include hardware and software that offer different ways to use computers and smartphones—for instance, by listening to content instead of reading it or entering text with your voice instead of the keyboard. Nothing gives you greater certainty that your product will work for people with disabilities and the technologies they rely on than testing with users.
Layer five: Specialist review
If your organization has an accessibility team, ask them to do User Acceptance Testing pre‑release. You can also hire vendors to audit for compliance with the international standard for accessibility, the Web Content Accessibility Guidelines (WCAG).
Where to start
You don’t have to include every single layer of accessibility testing right away. Start with any one or two layers and then add more layers as you get better at accessibility testing.
Remember, the goal isn’t to score high in a testing tool or even to meet a WCAG guideline, but rather to make your product or service available to all users.
A longer version of this sidebar appeared in Smashing Magazine.
From Horton, S., & Sloan, D. (2024). What Every Engineer Should Know About Digital Accessibility. CRC Press, Boca Raton, Florida.
Know About Accessibility 