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
Modernized fork of NEdit, with unicode support and AA text rendering
Learn Java the easy way!
A powerful editor and graphical debugger for code written in Scilab
Kile is a feature-rich LaTeX editor
Jexer - Java Text User Interface Library
TclTk-IDE for development and testing tcltk-apps
A hackable text editor for the 21st Century
Web IDE in single HTML file
IDLE Extensions
A syntax highlighting, code folding text component written in Swing
Open Source C & C++ IDE for Windows
Launch an external diff tool like WinMerge in Eclipse
A modern, lightweight yet powerful text editor
CodeLite: an open source, cross platform C/C++/PHP and JavaScript IDE