The following tools are used to maintain SLP Core including the SaaS and WordPress plugins.

VVV – Varying Vagrant Vagrants , a virtual machine environment for WP development as per the WP Core Development Getting Started guide.    They have a decent installing vvv guide.

SourceTree – a visual git repository manager.

phpStorm – an IDE for editing code, controlling Vagrant installs and sometimes even code commits (overlaps with SourceTree which has a better visual branch manager).  If you buy this get the individual/personal use license.