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IPNetInfo vs ICANN Lookup: catalog facts
IPNetInfo	ICANN Lookup
Free Freeware from NirSoft that may be redistributed free of charge.	Free Free public lookup service run by ICANN.
Windows	Web
Extracts IP addresses from pasted email headers Queries all five regional internet registries	Run by ICANN rather than a registrar or advertiser Uses RDAP instead of scraping WHOIS
Needs an internet connection and outgoing access to port 43 Official requirements list Windows 98 to Windows 10 only	Only shows registration data, with no DNS or mail diagnostics
Downloadable app	Web application
Closed source	Closed source
License: Freeware	License not stated
No account needed	Not stated if an account is needed
Needs internet	Needs internet
Official website Full listing and sources Checked October 8, 2026	Official website Full listing and sources Checked September 23, 2026

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