Notepad++ is a free source code editor which supports several programming languages running under the MS Windows environment.
This project, based on Scintilla edit component (a very powerful editor component) and 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 project is mature. However, as you can see it's a one-man-project, there're still some bugs and missing features. If you have any question or suggestion about this project, please drop me a mail, I'll love to hear from you. As well, if you have any feature request, you can always do the demand, but there's no warranty that I'll implement it.
You're encouraged to translate Notepad++ (if it is not present in the Download Section) and/or to translate the Notepad++ official site in your native language.