- Kiki [GNU GPL]
- Suneido [GNU GPL]
- Bloodshed Software (contains a lot of free compilers)
- DJGPP
- ActivePerl, ActivePython, ActiveTCL,...
- MinGW (Minimalist GNU For Windows)
- winGTK
- png2ico [GNU GPL]
- UMLet [???]
Ada:
Assembler:
- flat assembler [Other/Proprietary]
- NASM [GNU LGPL]
- WinDLX [Public Domain]
Basic:
- FreeBASIC
- XBasic
- wxBasic
- ScriptBasic
- Yabasic [GNU GPL or Artistic License]
C:
- gcc [GNU GPL]
Delphi:
- Lazarus [???]
Fortran:
- Open Watcom[Sybase Open Watcom Public License version 1.0]
- g95 [GNU GPL]
- GNU Fortran 95 [GNU GPL]
Haskell:
- Hugs 98
- Helium [GNU GPL]
- The Glasgow Haskell Compiler [Other/proprietary]
Java:
- Sun's Java [GNU GPL]
- jikes [IBM Public License]
- gcj [GNU GPL]
- Dependency Finder [BSD license]
- Ant [Apache License]
Lua:
- Lua [MIT license]
Mercury:
- Prolog [GNU GPL]
.NET
- The Mono project
- DotGNU
- SharpDevelop [GNU GPL]
Pascal:
- Dev-Pascal [GNU GPL]
- Free Pascal
- Inno Pascal
- Lazarus [???]
Perl:
PHP:
Prolog
Python:
Ruby:
- Ruby [GNU GPL]
Scheme:
IDE's:
- Dev-C++ [GNU GPL]
- Ultimate++ [GNU GPL]
- NetBeans [SPL (Sun Public License)]
- Eclipse [CPL (Common Public License)]
- RHIDE
- WideStudio [MIT/X Consortiun Licence]
- ArgoUML [BSD license]
- Boa Constructor [GNU GPL]
- Code::Blocks [GNU GPL]
Installer systems:
- Inno Setup [Other/Proprietary License]
- InstallJammer [MPL]
- FreeExtractor [Other/Proprietary License]
- Nullsoft Scriptable Install System
- UPX [GPL]
- WiX [CPL]
CVS:
- GUI front-ends for CVS [GNU GPL]
- InnoCVS [GNU GPL]
- TortoiseCVS [GNU GPL]
Subversion:
- TortoiseSVN [GNU GPL]
Decompilers:
- Boomerang [GNU GPL]
- JODE [GNU GPL]
- JReversePro [GNU GPL]
- DCompiler [GNU GPL]
- NASM [GNU LGPL]
- HelpDeco [???]
Libraries
- GTK+ (GIMP Toolkit) [GNU LGPL]
- GTK+ for Windows [GNU LGPL]
- wxWindows
- The Fast Light Toolkit [GNU LGPL]
- gtkmm [GNU LGPL]
- SDL (Simple DirectMedia Layer) [GNU LGPL]
- wxPython [wxWindows License]
- WinPcap (Windows Packet Capture Library) [BSD]
- Little cms [GNU LGPL]
- Allegro [giftware]
- The GUI Toolkit, Framework Page
- Mesa3D [MIT-style license]
- G3D [BSD]
- VTK (The Visualization Toolkit) [Other/Proprietary License???]
- DirectP2P [GNU GPL or GNU LGPL] (development seems not to have started yet...)
- OpenPTC [GNU LGPL]
- Trivial Portable Framework Library [BSD, GPL, LGPL]
- FFmpeg [GNU LGPL]
- JWindows [GNU LGPL]
- Loris [GNU GPL]
- NTL [GNU GPL]
- Toolbar2000 [GNU GPL]
- IT++ [GNU GPL]
- Blitz++ [GNU GPL]