Mine Top3 apps are:
It’s a build in app that proof-reads everything you write. With its help you ensure typo free and grammatically correct messages. I usually use the free basic version but have also tried the premium version for a week. It’s worth updating if you write a lot.
2. Sublime Text
A free text editor for code that I have used for everything I have done on the web as a beginner. It’s an open source project and they periodically ask for contributions. I should make one soon since it has been super useful.
This app is great for brain exercises during breaks or on the go. Instead of playing some usually useless online games play games that actually develop your memory, attention and problem solving skills.