IntelliJ IDEA - JetBrains
Source-code: https://github.com/JetBrains/intellij-community
MonoDevelop
Anjuta DevStudio
Lazarus IDE
Lazarus is a professional open-source cross platform IDE powered by Free Pascal
SharpDevelop
#develop (short for SharpDevelop) is a free IDE for .NET programming languages. - icsharpcode/SharpDevelop
Apache NetBeans
Apache NetBeans
Komodo IDE
Code faster with Komodo IDE from ActiveState. Best multi-language IDE for today's web languages - Python, PHP, Perl, Golang, Ruby and more.
Light Table
Light Table is the next generation code editor. Light Table Connects you to your creation with instant feedback and showing data values flow through your code.
Brackets.io
Brackets is a lightweight, yet powerful, modern text editor. We blend visual tools into the editor so you get the right amount of help when you want it. With new features and extensions released every 3-4 weeks, it's like getting presents all year long.
Spyder IDE
Website for Spyder, the Scientific Python Development Environment
PyDev
PyDev Manual
Visual Studio Code
Visual Studio Code is a code editor redefined and optimized for building and debugging modern web and cloud applications. Visual Studio Code is free and available on your favorite platform - Linux, macOS, and Windows.
Visual Studio - IDE for software developers
Visual Studio dev tools & services make app development easy for any platform & language. Try our Mac & Windows code editor, IDE, or Azure DevOps for free.
Atom.io
A hackable text editor for the 21st Century