While these testing tools can identify many accessibility and Web Content Accessibility Guideline (WCAG) errors, they are not a replacement for the full WCAG. It is recommended to use these tools to help facilitate human evaluation of web content.
WAVE
The WAVE web accessibility evaluation tool is available as an API, testing engine and browser extensions for Chrome, Firefox and Edge. Because the extension runs entirely within your web browser, it can check intranet, password-protected, dynamically generated, or sensitive web pages.
WAVE Chrome, Firefox, and Edge Extensions (webaim.org)
Axe
The Axe accessibility testing suite includes development, audit, and monitoring tools as well as a free browser extension for Chrome.
axe: Accessibility Testing Tools and Software (deque.com)
Axe for Designers
An accessibility plugin for Figma that has features like A11y Scan, WCAG Color Contrast Checker, Focus Order, and Annotations. This plugin helps you identify accessibility issues before your design goes into development.
Axe for Designers: A Free Accessibility Plugin (Figma Community)
Accessibility bookmarklets
Bookmarklets are small snippets of JavaScript executed when user clicks on them. These bookmarklets add new features to your web browser to aid in accessibility testing.
49 Accessibility Bookmarklets You Can Use For A11Y Testing • DigitalA11Y
WebAIM contrast checker
WebAIM’s colour contrast checker, which is also available as an API and bookmarklet.
Screen readers
Non-Visual Desktop Access (NVDA)
NVDA is a free screen reader tool for computers running windows. NVDA works on Firefox, Chrome, and Edge.
Job Access With Speech (JAWS)
JAWS is a paid screen reader tool for computers running windows. JAWS has historically been the most widely used screen reader and is largely considered best-in-class. JAWS works on Firefox, Chrome, and Edge.
VoiceOver
VoiceOver is a free screen reader for computers running MacOS and mobile devices running iOS. VoiceOver is the most popular screen reader for Apple users as it comes built-in to the operating system. VoiceOver works best with Safari. VoiceOver works with other browsers, but some errors may be introduced.
Accessibility - Vision - Apple (CA)
PDF testing tools
Foxit PDF Editor
Foxit PDF Editor’s Accessibility Checker can quickly run a full check on a file to determine whether it meets WCAG standards for accessibility. It produces a detailed report about its degree of accessibility, allowing users to pinpoint where issues are and how to fix them using the Tag Editor.
PDF Accessibility Checker
PAC is designed to easily identify all of the machine verifiable success criterion of ISO 14289-1 (PDF/UA) and WCAG (Web Content Accessibility Guidelines).
PDF Accessibility Checker (PAC) 2021 - PDF/UA Foundation (pdfua.foundation)