Atom is a free and open-source text and source-code editor for macOS, Linux, and Windows with support for plug-ins written in JavaScript, and embedded Git control.

[9][10] Atom is a "hackable" text editor, which means it is customizable using HTML, CSS, and JavaScript.

[16] Atom uses Tree-sitter to provide syntax highlighting for multiple programming languages and file formats.

All types of packages, including but not limited to: Syntactic highlighting support for languages other than the default, debuggers, etc.

[31] Atom was made fully open source in May 2014 under the MIT License, including its desktop framework Electron.