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W3Techs Site Info vs WhatWeb: catalog facts
W3Techs Site Info	WhatWeb
Free The website lookup, bookmarklet and extensions are free to use; a separate API is offered.	Free Free and open source under GPLv2.
Web, Browser extension	Windows, macOS, Linux, Command line
Identifies CMS, language, web server and hosting provider Bookmarklet and Firefox and Chrome extensions for the current page	Fingerprints hundreds of web technologies via plugins Adjustable aggression levels
Shows only what can be detected from outside the site Website carries advertising	Command-line only Intended only for authorized testing
Web application, Browser extension	Downloadable app
Closed source	Open source
License not stated	License: GPL-2.0
No account needed	No account needed
Needs internet	Works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 24, 2026

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