Zend and Ioncube
The Zend version requires Zend Optimizer to be installed on the server. Zend Optimizer is free and many hosts either already have it installed or will be willing to install it for you.
Ioncube can either be installed server wide or in most cases you can upload run-time loaders to your hosting account to use the files. The loaders are free and you can get them for almost any OS from Ioncube.com. We distribute the most popular loaders with the program.
What is the difference?
You will not see a difference in performance between Zend and Ioncube.
Switching between Zend and Ioncube
You can easily switch between Zend and Ioncube versions.
Be sure to upload the files in BINARY mode! Auto or ASCII mode will corrupt them.