IDE and Text Editors
Atom
Codepen
CodeSandbox
Eclipse
Jetbrains Tools Suite
Personal comment:
Recommend it a lot for the variety of tools that they're offering. Also some of their tools have a free version available so look out for that.
Repl.it
Personal comment:
Recommend it a lot when starting out with back-end development. The tool also has a hacker community behind it so I recommend you to take a look at it.
Vim
Personal comment:
I gotta say that this is probably one of the coolest text editor I've experienced so far. Features ton of shortcuts for navigating and manipulating through the file and has an active ecosystem of plugins.
Visual Studio (IDE)
Personal comment:
I recommend this but don't be overly reliant ;p
Visual Studio Code
Personal comment:
THIS VERY MUCH!
Personal comment:
Also it works offline and mainly used for front-end frameworks so it's a double plus for me.