Tools

IDEs

Multi-Purpose: Visual Studio Code (free)

.NET / C#: Visual Studio (free)

Android App Dev: Android Studio (free)

Python: Pycharm (free)

Java: IntelliJ IDEA (free)

C / C++: CLion (free for students)

Git

GitKraken (free)

Sourcetree (free)

Fork (free unlimited evaluation)

Databases

Server: MySQL Server (free) or MongoDB (free)

Reading database: HeidiSQL (free) or Datagrip (free for students)

Designer: DB Designer (free)

Others

.NET Decompiler: dotPeek (free)

API-Testing: Postman (free)

Cheap VPS-hosting: GalaxyGate