NexWhoisD - Open Source Whois Server
NexWhoisD is a threaded whois server for domain and IP information. Data is stored in a MySQL database. It currently supports Domain, IP Netblock (including upstream resolution), Organization, and Point-of-Contact queries. It is RFC 3912 compliant.
For extra features like bug reporting, forums and SVN see the projects main sourceforge page.
NexWhoisD and all accompanying documentation and supporting files are licensed under the Apache 2.0 license. A copy of this license is provided here and the accompanying NOTICE file can be ready here.