Phoenix is a modern open-source Code Editor for the web
Apache NetBeans
A web based file manager, web IDE / browser based code editor
Kotlin code completion, diagnostics and more for any editor/IDE
Learn Java the easy way!
A powerful editor and graphical debugger for code written in Scilab
TclTk-IDE for development and testing tcltk-apps
A hackable text editor for the 21st Century
Web IDE in single HTML file
IDLE Extensions
Open Source C & C++ IDE for Windows
Launch an external diff tool like WinMerge in Eclipse
A modern, lightweight yet powerful text editor
Electronic design and programming tools suite like Eagle, MpLab
Develop AMX NetLinx projects in the Sublime Text editor.
Develop Crestron Simpl+ modules in Sublime Text.
Graph algorithms interpreter, IDE, debugger, 3D visualizations.
Python script coding editor that debugs as you write