GNU Dr. Geo, be a Geometer!

A program to design and manipulate interactive geometric sketches.
It helps kids to explore geometry. Distributed with its source code, it is Modify-me-Ready and it runs on GNU/Linux, Windows and Mac OS X.

Dr. Geo demo

Dr. Geo is an education-oriented software package. It's an observatory for exploring the properties of geometric objects in an interactive way, in opposition to static sketch drawn on a sheet of paper. The user interface is designed to be simple but efficient for young users. In spirit, it is a free education tool for schools where freedom and equality matter.

Its second aim is to be open and easy to study, modify and extend. It is distributed with source code that you can modify while using it. Ten-year-old kids use Dr. Geo to explore Euclidean geometric sketch; agile kids extend and program it with its embedded dynamic Pharo language and user interface.

Just like other interactive geometry software such as Cabri, Cinderella, Geogebra or Carmetal, Dr. Geo enables the user to create a geometric sketch, and manipulate it according to its constraints. What sets Dr. Geo apart from other geometry software is the possibility of studying, and even modifying/extending its source code while s/he is using it to create a figure. It is the GNU spirit in action!

Downloading Dr. Geo

The latest release, 19.09b, can be downloaded at

Source code

The Dr. Geo source code is at Launchpad, To build the executable:

  • read the INSTALL document which resides in the Dr. Geo repository;
  • install the Pharo programming system (licensed under the MIT license);
  • install Dr. Geo according to instructions.

But do not forget, the Dr. Geo source code can also be edited from the integrated source code browser while running the program.


Documentation and help are found at

How to contact the Dr. Geo team

Social network
Follow us on Mastodon.
Mailing list
There is a mailing list for all kinds of discussions related to Dr. Geo.
There is also a web-based forum at with dedicated topics:
Instant chat
The instant discussion group is You can install IRC software to connect, or use the web client (Nickname: your name, Channel: #drgeo).

Getting involved

Development of Dr. Geo, and GNU in general, is a volunteer effort, and you can contribute. For information, please read How to help GNU. If you'd like to get involved, it's a good idea to join the discussion forum.

Use the software!
Learn and use Dr. Geo. You may encounter bugs or you may have ideas for new features. Several were developed at user requests.
Contact: forum, email, bug report whatever suit you.
We have pretty complete user guides in French and English. Its source is the Texinfo format—as requested for any GNU software. Help is welcome for proofreading, formatting contents or contributing chapters.
Documentation source repository
Dr. Geo user interface needs to be localised to as many languages as possible. To participate in this effort, visit its translation page. Translation is done online from your web browser. You only need a Launchpad account.
For development sources, issue trackers, and other information, please see the Dr. Geo project page.
See the open bug tickets.
The author of Dr. Geo is Hilaire Fernandes <hilaire AT>; he's still maintaining it.


Dr. Geo is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.