I Use Zulip as it is a very powerfu group chat & Is fille d with apps from every available platform.
Not to mention that I got addicted to Open-Source Software because of them.
Really Helpful Tool
Google Drive is far by the best & most user-friendly Online storage facility that one can avail
They allow 15 GB storage on a free account!!!
Also, very fast & easy to handle
Android studio is the best platform for app development & screwing around with the code
Also very user-friendly
Google Maps is the best app for maps ever.
Full of perfectly accurate maps, it also shows one's location precisely, which is very essential
Best Software for creating Windows Form Applications & Command Line programs.
Very Easy to use
Skype is far by one of the best video calling apps I've ever used(After Google Duo)
It has a very simple User Interface, hence is a favorite of mine.