PHP AJAX Instant Domain Availability Checker
PHP AJAX Instant Domain Availability Checker Demo

Features

1. AJAX! Receive results instantly
2. Efficient! Checks whether DNS entries exists, if not, performs an additional optional WHOIS query and interprets the results.
3. Up to 3 checks to ensure a domain is truly and really available. Checks can be disabled for performance and scale, at the cost of accuracy.
   
4. No external PHP/JavaScript libraries required. To install, just do a php include to add it to your page. It is that easy!
   
5. Supports most domains. Additional domains can be done at request. Please test/ask before buying
   
6. Supports Recaptcha to prevent misuse of the script. Can be disabled.
7. Supports limitation of TLDs allowed to be checked (i.e. allow checking of only a list of TLDs)
   
8. Keeps a list of available domains in a separate box. Can be disabled.
9. Big Availability Text to show whether the domain is available. Can be disabled.
   
10. No MySQL required. Doesn't require a database
11. Affiliate Friendly - Allows specifying a generalized customizable link for visitors to register whenever any searched domain is available
12. Affiliate Friendly - Allows specifying a customizable link on a per TLD level for visitors to register a domain whenever any searched domain with that TLD is available
13. Supports Full Whois Query display for an unavailable domain with recaptcha support. Can be disabled.
14. Customizable Language - Just replace the variables in $language to your language
15. Tested to be working under PHP 4.4.7 and PHP 5
16. HTML4 Strict Compliant.
17. Less than 100 lines of HTML code. Easy customizability
18. Only US$9.99 for the whole package

The following is a live demo. For every recaptcha entry, the script is configured to allow TEN domain checking / whois queries.

Update Dec 2019: Recaptcha function does not work with the latest library

Find it useful? Download it now.

Note: If the checker is configured to check domains by performing Whois checks (one of the 3 checking methods), it would be limited to as much as the domain registrar will allow as they have a limit on the number of times the domains can be checked. Without the Whois method enabled, you have practically unlimited checks, but at the cost of accuracy (i.e. some domains may show as available, when they are not)