What it does
ARIN Whois/RDAP provides registration information for IP resources, organizations and points of contact, with a web interface for readable results.
Enter an IP address, CIDR range, ASN or entity identifier and use a search filter when automatic type detection is too broad. ARIN’s web interface renders RDAP JSON as readable resource and related-entity records. IP and CIDR searches do not support wildcards; name searches have different rules. Check Source Registry when a response includes another registry’s data, since field names and publication can differ. ARIN describes its public Whois content as organizational information associated with number resources, separate from confidential account-profile information. Treat the registrant and contact as allocation context rather than the individual currently using an address.
Strengths
- Registry-operated number-resource lookup
- Web interface over structured registration data
Watch out for
- Registration records do not identify an individual current user
Sources
- Using Whois - American Registry for Internet Numbers (Oct 26, 2026)