ZendGuard

Zend Guard is the industry leading solution for PHP IP protection. Zend Guard provides independent software vendors and IT managers with the ability to safely distribute and manage the distribution of their PHP applications while protecting their source code.

Zend Optimizer is a free application that runs the files encoded using Zend Guard and enhances the overall performance of your PHP applications. As software vendors write more and more commercial applications in PHP it is critical that their intellectual property (all their hard work) is protected. With more applications providing evaluation copies and electronic downloads it is an even more complicated to insure that they are being distributed securely, whether free, for evaluation or for commercial sale.
Zend Guard (formerly Zend Encoder) protects your applications from reverse engineering and unauthorized customization by providing encoding and obfuscation. It further protects from unlicensed use and redistribution by providing comprehensive licensing support. This combined functionality makes software distribution worry free.