UnDraw
Open-Source, Free, Themable Illustrations. The best alternative to stock images.
Choose an illustration, change its theme, export as an .svg or .png
Visual Studio Code
Open source, cross platform code editor, designed with web development in mind. Comes with Intellisense and integrated Git Control. Ready to use out of the box, no need to install tons of 3rd party extensions, like with Atom.
Hyper
A cross platform terminal built on top of React.js. Open source, customisable and even Inspectable.
Google Fonts
Customisable, blazing fast web fonts.
Import fonts as you go
UpLabs
My favourite place to find design inspiration.
My upvoted items on uplabs, https://www.uplabs.com/users/foreggs/
Android Asset Studio
Awesome Material Design Android Assets, mostly icons.
Slack
Best for team programming assignments, managing tasks and many more.