If you want to use InvoicePlane you have to follow these requirements:
A webserver / webhost with the following specifications:
- MySQL > 5.x
- PHP > 5.5.0 with the following PHP extensions:
- php-mcrypt (How-To)
- and a modern and up-to-date web browser.
Please notice that PHP 5.5 is no longer supported and should not be used anymore for producton environments!