axe-core
axe-core is the open-source accessibility testing engine maintained by Deque Systems that powers most major automated accessibility scanners, including AccessComply's.
Detailed explanation
axe-core is a JavaScript library that runs against a rendered DOM and returns a set of WCAG-mapped violations. It is the default engine inside Google Lighthouse, Microsoft Accessibility Insights, Cypress-axe, Playwright-axe, the React Testing Library, and most commercial accessibility platforms.
axe-core has zero false positives by design — Deque's rule team rejects rules that cannot be tested deterministically. This makes it conservative: axe-core finds roughly 30-40% of WCAG issues automatically; the rest require manual or assistive-technology testing. axe-core is licensed Mozilla Public License 2.0 and is free to use commercially.
How this applies to Shopify stores
AccessComply runs axe-core against every page of the storefront via headless Chromium. We then layer Shopify-specific rules (theme version, app conflicts, Liquid antipatterns) and visual diffing on top of axe so merchants get a complete picture, not just the automated 30%.
Primary source: github.com