Aquamacs is an Aqua-native build of the powerful Emacs text editor. By "Aqua-native," we mean more than just the fact that this version of Emacs runs as a standard OS X application. Aquamacs features extensive customization: it will feel and behave mostly like an Aqua program - while still being a real GNU Emacs with all the ergonomy and extensibility you've come to expect from this world-class editor.