GNU Emacs
Emacs is a simple text editor which is available for Windows, macOS, and Linux operating systems. It can be used to edit and manage text files, test codes, etc.
Emacs can be used to edit source code, shell scripts, directory listings, web pages, and emails. Keyboard commands can also be used to automate tasks, making it convenient for the developers.
Furthermore, Emacs also serves as an IDE, providing facilities for program compilation, execution, and testing in addition to text editing.