Check out the overview of supported PHP versions
Our recommendation is to always run the most modern stable version of PHP that your application supports. It is almost always faster, more secure and better maintained. It will also give your application the longest possible potential life, as opposed to choosing tech that is soon to be discontinued.
Supported PHP Versions
PHP 7.1 - receives all new Servebolt features
All new WordPress & Drupal-sites and most other applications should run PHP 7.1.
PHP 7.0 - no new features added any more, active development is ending soon - security fixes only.
Note Magento! At the moment Magento 1 and 2 are limited to running PHP 7.0, Magento 1.0 needs Inchoo which will reward you with a much better performing site than running it on outdated PHP 5.6.
Security updates only
PHP 5.6 (legacy support, security fixes only) If your web application is still running PHP 5.6, you should plan to upgrade to PHP 7.1 as soon as possible. We do no longer provide PHP 5.6 for new clients.