NethernetWhois allows you complete power over all settings, has online admin, and only one line of code to edit. It is the easiest way to allow your customers to register domains via the Internet. It features: Unlimited Domain Registrations, Automated mailing of all parties involved, Users can either Register or Modify a domain, Registration information for registered domains is displayed, Support for SSL Ordering for enhanced security, Built in Optional Credit Card Processing, and basic Syntax, and more.

This script simply does a whois for the domain you enter, and then indicates if the domain has already been taken or not.

CdomainPlus is a Domain Lookup Utility Perl CGI script that allows users to check the availability or view the details of one or more Domain Names on the Internic's Database. It features: Simple Single Search that allows the user to check one domain at a time, A Domain Name Wizard that allows the user to construct several domain name possibilities by answering a few questions, A Global Search that allows the user to enter in a domain and search all Internic domain extensions, Templates support, Increased Error Checking, and more.

CdomainPro features domain lookups in over 160 extensions (i.e., .co.uk, .com.au) across 50+ nTLDs (i.e., .uk, .de, .ca, .au)in addition to .com, .net and .org domains. You can also add more nTLDs to CdomainPro by simply editing a text file. CdomainPro features two forms of lookups, either second level domain with TLD checked, or FQDN. In addition, CdomainPro includes all the CdomainPlus features and benefits.

CdomainLite is the same program as CdomainFree with the exception that it allows you to remove the links and copyright information from the HTML source.