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