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Webbkoll vs HTTP Observatory: catalog facts
Webbkoll	HTTP Observatory
Free Free to use, run by a non-profit foundation.	Free Free to use on the MDN website.
Web	Web
Covers cookies, third parties, HTTPS and security headers in one report Checks HTTP to HTTPS redirects	Checks CSP, HSTS and other security headers Actionable recommendations tied to MDN documentation
Some sites fail to scan correctly Simulates a single default browser visit	Focuses on headers and configuration, not full vulnerability scanning Only works for publicly reachable sites
Web application	Web application
Closed source	Closed source
License not stated	License not stated
No account needed	Not stated if an account is 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.