Google's Accessibility Scanner app, and how to test a website

Accessibility Scanner runs on Android phones and tablets and checks the screens of apps installed on the device. According to Google's help page, it looks at four things:

• Content labels, such as a button with no name for TalkBack to read
• Touch target size
• Clickable items
• Text and image contrast

You can scan one screen with a snapshot, or record a flow and get a screenshot of each screen you pass through. Findings are outlined on the screenshots, with a list view alongside. Google's page is clear that it does not replace manual testing, and that it cannot capture secure windows, the kind many banking and payment apps use.

Use it if you build, test or buy an Android app. It is free, it needs no code, and it catches the common problems in a few minutes. Pair it with TalkBack, Android's screen reader, to hear how the app actually reads out.

For an iPhone app, the closest equivalent is Apple's Accessibility Inspector, which ships with Xcode.

Google's help page describes the app as a tool for Android apps. A website needs a tool that reads the page's HTML and applies web rules to it. The four things the app looks at all have web counterparts in WCAG:

• Content labels are accessible names on buttons, links and images, and labels on form fields.
• Touch target size is WCAG 2.2's 24 by 24 pixel minimum, success criterion 2.5.8, covered in the WCAG 2.2 checklist.
• Clickable items means controls built from real button and a elements, which also makes them work from a keyboard. See keyboard navigation.
• Contrast is WCAG 1.4.3, with its 4.5:1 ratio for normal text. See fixing colour contrast.

The scan at the top of this page loads a website in a real browser and runs axe-core against WCAG 2.2 A and AA. Every failing element is outlined on a screenshot and tied to the success criterion it breaks. It also resolves contrast over gradients and background images, which most web checkers leave for a person to judge.

There are other free options for websites too. Lighthouse is built into Chrome, and WebAIM's WAVE marks issues on the page itself.

Test each with the tool made for it. Organisations that publish both often have to: the ADA Title II rule for state and local governments and the European Accessibility Act both cover mobile apps as well as websites. Automated tools on either side only find the machine-checkable problems, so plan a manual pass with a screen reader for the rest.