Leo’s Home Page

"Leo is a revolutionary step in the right direction for programming."―Brian Takita
"Leo is the best IDE that I have had the pleasure to use. It has totally changed not only the way that I program, but also the way that I store and organize all of the information that I need for the job that I do."―Ian Mulvany
"When first I opened Leo, it was out of curiosity. But having used it, I'll never go back. They'll have to pry Leo out of my cold, dead fingers!"―Travers A. Hough

Leo is a PIM, IDE and outliner that accelerates the work flow of programmers, authors and web designers. Leo's unique features organize data in a revolutionary way:

  • Leo outlines are views on an underlying graph.
  • Outline nodes can reside in many places within a single outline.
  • Leo is fully scriptable in Python.
  • Leo scripts have full access to Leo's source code and all outline data.
  • Outline-oriented markup generates external files from outlines.
  • Learn why Leo is special.
    Learn about Leo in two hours.


  • Leo is Open Software, written in pure Python.
  • Leo is a PyQt app that runs on Linux, Windows and MacOS.
  • Leo works well with emacs, xemacs, vim, and ipython.
  • We welcome your questions and comments!
    Ask us anything at the medium traffic leo-editor Google Group.
    If you use Leo, please send us a postcard, telling how you use Leo. Thanks!

    Here is a slightly reduced screenshot of Leo's main window: