Leo Editor is described as 'Leo is an open source text editor/outliner that features clones (virtual copies of outline nodes) as its central tool of organization, navigation, customization and scripting' and is an app in the Development category. There are more than 10 alternatives to Leo Editor for a variety of platforms, including Windows, Linux, Mac, BSD and Chrome OS. The best alternative is Atom, which is both free and Open Source. Other great apps like Leo Editor are GNU Emacs (Free, Open Source), ReText (Free, Open Source), Graviton Editor (Free, Open Source) and Caret (Free).
ReText is a simple text editor for Markdown and reStructuredText documents with syntax highlighting and optional live preview. It is written in Python using Qt libraries, able to run on any platforms (Linux and BSD are officially supported).
Judge0 IDE is a free and open-source online code editor that allows you to write and execute code from a rich set of languages. It's perfect for anybody who just wants to quickly write and run some code without opening a full-featured IDE on their computer.
PyScripter is a free and open-source Python Integrated Development Environment (IDE) created with the ambition to become competitive in functionality with commercial Windows-based IDEs available for other languages.
A text editor for GNOME that combines simplicity with power. Scribes focuses on streamlining your workflow. It does so by ensuring common and repetitive operations are intelligently automated. And also by eliminating factors that prevent you from focusing on your tasks.