The five RIRs are ARIN (North America), RIPE NCC (Europe, Middle East, Central Asia), APNIC (Asia-Pacific), LACNIC (Latin America), and AFRINIC (Africa). IANA hands them blocks; they sub-allocate to ISPs and other LIRs.
IPFerret's WHOIS / RDAP tool queries the appropriate RIR for any IP and follows cross-RIR redirects automatically.
Try it on IPFerret
See also