Sam’s Whois is a free php class with supporting scripts which make adding a
domain name whois lookup to your website incredibly simple. The scripts
were written by me, Sam, hence the name. Imaginative, huh?

Website for more info and documentation: http://www.phpace.com/scripts/sams-whois/

Main Features

    * All major tlds supported (including com, net, org, info, biz, us, co.uk, org.uk, etc)... *this may be slightly out of date now...
    * Optionally automatically redirect a query to the authoritative whois server for a tld where appropriate (.com and .net).
    * CSS-based design for easy integration with your existing website design.
    * Free to use (see the licence page for full details)
    * Can cache whois lookup results for a specified amount of time, reducing bandwidth and system usage.
    * Optionally require users to enter a randomly generated code, displayed as an image, for each lookup to stop people using scripts to abuse the system.
    * Comes with a detailed and heavily commented example script fully illustrating usage.
    * Easy installation – Basic version requires only 1 line of code. View the quickstart guide here.
    * Optionally clean whois data of extraneous text (for some tlds).
    * Easily limit which tlds are supported with one line of code.
    * Optionally hilight main fields in the whois data for extra clarity.