Phoenix is a modern open-source Code Editor for the web
A free C, C++ and Fortran IDE
an OSGi-based Swing Application Framework
Kile is a feature-rich LaTeX editor
Extensible HTML5 app for real-time collaborative projects
A tiny and lightweight IDE for the Go programming language
Graph algorithms interpreter, IDE, debugger, 3D visualizations.
A modernized, platform independant version of Dev-C++