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WhatWebW3Techs Site Info
Free

Free and open source under GPLv2.

 Free

The website lookup, bookmarklet and extensions are free to use; a separate API is offered.

Windows, macOS, Linux, Command line Web, Browser extension
  • Fingerprints hundreds of web technologies via plugins
  • Adjustable aggression levels
  • Identifies CMS, language, web server and hosting provider
  • Bookmarklet and Firefox and Chrome extensions for the current page
  • Command-line only
  • Intended only for authorized testing
  • Shows only what can be detected from outside the site
  • Website carries advertising
Downloadable app Web application, Browser extension
Open source Closed source
License: GPL-2.0 License not stated
No account needed No account needed
Works offline Needs internet

Checked September 24, 2026

Checked September 23, 2026

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