Pa11y 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.

Established

OSS community · since 2013

Widely used

Siteimprove · since 2003

• Free, scriptable and trivially added as a CI gate.
• Tests a sitemap of URLs in one run, unlike page-by-page extensions.
• Self-hosted dashboard for tracking without a vendor.

• 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.

• No guided manual testing or remediation workflow.
• Testing authenticated or interactive states requires scripting actions.
• Maintenance activity has been intermittent.

• 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.

Teams wanting free automated accessibility gates across many pages.

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