axe-core
The open source accessibility testing engine behind many automated accessibility checks, including browser extensions and integrations for Playwright and Selenium. It scans a rendered page against WCAG rules and reports violations with the element, the rule and how to fix it, so you can add accessibility checks to your automated suite and CI.
7.6k
GitHub · Sept 2026
Tool
Web Development
Deque Systems
Intermediate
Free
What it is
axe-core is an open source JavaScript library from Deque Systems that tests web pages for accessibility problems. It runs inside the browser on the rendered page and checks it against rules mapped to the Web Content Accessibility Guidelines (WCAG) and common best practices. It is licensed under MPL-2.0 and is the engine inside many other tools, including browser extensions and test framework integrations.
What it finds, and what it does not
axe-core detects problems that can be checked by code: missing form labels, images without text alternatives, insufficient colour contrast, invalid or misused ARIA attributes, missing document language, duplicate IDs in some contexts and more. Its README states that it finds on average 57% of WCAG issues automatically and aims to return zero false positives, bugs notwithstanding. The remaining issues, such as a confusing focus order, keyboard traps in custom widgets or unhelpful alternative text, need manual testing with a keyboard and a screen reader.
How testers use it
- In automated tests: official integration packages exist for common frameworks, such as @axe-core/playwright for Playwright and Deque's Selenium integrations for Java and other languages. A test loads a page, runs the scan and fails if new violations appear.
- In CI: scanning key pages on every pull request catches regressions before release.
- By hand: browser extensions built on axe-core help while exploring a page.
Is it worth your time?
Yes, if you automate web tests. Adding a scan to a few key journeys takes minutes and catches a class of bugs most suites ignore. Read each violation's help link; they explain the rule and the fix clearly.
Prerequisites
A working browser automation setup and a basic understanding of WCAG principles.
Free or paid?
axe-core is free and open source. Deque also sells commercial products and training built on it; you do not need them to use axe-core in your tests.
Common questions
Does zero violations mean the page is accessible? No. It means no automatically detectable issues were found. Manual checks are still needed.
Should every test run a scan? Usually no. Scan key pages and states, and keep the scans fast and focused.
Ready to start?
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