axe-core vs Siteimprove

Free and open source

Quote on request

Free and open source. You pay in engineering time and CI minutes.

Enterprise annual contracts priced by pages crawled and modules.

Everything, self-hosted

Free browser extension for single-page checks.

Category standard

Deque Systems · since 2015

Widely used

Siteimprove · since 2003

• Effectively zero false positives, which is why it became the industry default.
• Integrates into any existing test suite in a few lines.
• Free, actively maintained, and aligned with WCAG updates.

• Scans entire large sites and assigns findings to content owners, not just developers.
• Combines accessibility with SEO and content quality in one governance view.
• Reporting suited to demonstrating compliance progress to executives and regulators.

• Automated rules detect roughly a third of WCAG issues — the rest need human testing.
• A library, not a workflow: no dashboards, tracking or reporting.
• Only evaluates the DOM state it is given, so dynamic states need explicit test coverage.

• Expensive and aimed at organisations with a governance function.
• Weak fit for application testing as opposed to content sites.
• Limited shift-left developer tooling compared to Deque.

Any team that wants accessibility checks inside their existing automated tests.

Universities, government and large content organisations with legal accessibility obligations.