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 (that ensures the higher execution speed and smaller size of the program), is under the GPL Licence.

This software is available free of charge from Notepad++.

Windows

For more information about this software, see this GROK article: Notepad++: LSU Overview