PHP Modules Available on the Server
This article will help you find out which PHP modules are available on the server with the current settings.
This is the easiest method for doing this without code. Another method is to add a phpinfo page (not described here). These can be changed using the PHP Selector. See KBA: Changing PHP Settings
Steps
Login to your Plesk panel and click PHP Settings
Click the link View the phpinfo() page
Here you can see what PHP modules are available with the current settings.