Notepad++ is a free open source notepad replacement and code editor with nice features. It supports syntax highlighting for many languages and has an extension system as well. Developed by Don Ho
License: Open Source
Aquamacs Emacs is a highly customizable and powerful text editor that excels in complex programming environments, while Notepad++ offers a lightweight and user-friendly experience with good support for various programming languages. The choice between them depends on the user's need for customization and extensive features versus simplicity and speed.