Compete Site Analytics - provides information for every site on the internet including site traffic history and competitive analytics; a list of available promotional codes across thousands of online retailers; and site-specific trust scores based on up-to-the-minute data from Compete and third party security services.

Your site or application can display some of Compete's most powerful data by using the Compete Site Analytics API.

Link back to detailed documentation - http://developer.compete.com/

Other Links:

Wiki markup tips: http://developer.compete.com/public/Mashery/help/markdown.php

Terms of Use: http://developer.compete.com/index.php/Api_terms_of_use

Wrappers

.NET wrapper: http://www.codeplex.com/CompeteNET

PHP5 wrapper: http://torrentialwebdev.com/blog/archives/107-PHP5-Compete-API-Wrapper.html

PHP5 wrapper in the PEAR repository: http://pear.php.net/package/Services_Compete/