ARIN operates several RESTful web services:
- RDAP is a standardized, Whois replacement protocol using JSON over HTTP. All 5 RIRs operate RDAP services. More information on RDAP may be found here.
- Whois-RWS is a proprietary protocol specific to ARIN and predates RDAP. The specification for Whois-RWS can be found here.
- Reg-RWS is a proprietary protocol for registering IP address assignments with ARIN by ARIN customers. The specification for Reg-RWS can be found here.
A list of ARIN authored software for RDAP can be found on the RDAP page.
In addition, ARIN has authored a set of command-line Ruby clients which utilize both Reg-RWS and Whois-RWS. These scripts are known collectively as ARINCli. More information can be found on these scripts on the ARINCli project page, and information on each script may be found here.
ARINWhois.NET is a .NET client library for Whois-RWs written by Max Hortsmann. More information can be found on it’s GitHub project page.