Notepad++ is a free source code editor and Notepad replacement, which supports several programming languages, running under the MS Windows environment. This project, based on the Scintilla edit component (a very powerful editor component), written in C++ with pure win32 API and STL, is under the GPL Licence. This project is mature. However, as you can see it's a one-man-project, there are still some bugs and missing features.

Download