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W3C Link Checker vs muffet: catalog facts
W3C Link Checker	muffet
Free Free to use on the W3C website.	Free Free and open source.
Web	Windows, macOS, Linux, Command line
Checks anchors as well as full URLs Recursive crawling with a configurable depth	Fast concurrent crawling Fits easily into CI pipelines
Plain interface with a text-heavy report Works best when the pages already have valid markup	Command line only, no graphical interface Focused on links rather than wider SEO or markup checks
Web application	Downloadable app
Closed source	Open source
License not stated	License not stated
No account needed	No account needed
Needs internet	Not stated if it works offline
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.