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Nu Html Checker vs Rocket Validator: catalog facts
Nu Html Checker	Rocket Validator
Free Free to use on the W3C website.	Paid Paid subscription service with a free trial.
Web	Web
Checks against current HTML conformance rules rather than old doctypes Accepts a URL, a file upload or pasted markup	Site-wide HTML and accessibility checks in one report Up to 5,000 pages per report
Checks one document at a time Behavior is described as experimental and subject to change	Paid service after the trial Requires an account
Web application	Hosted service
Closed source	Closed source
License not stated	License not stated
No account needed	Account needed
Needs internet	Needs internet
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.