Python Tutor -- http://pythontutor.com/ -- helps people overcome a fundamental barrier to learning programming: understanding what happens as the computer executes each line of a program's source code.

Using this tool, you can write Python, Java, JavaScript, TypeScript, Ruby, C, and C++ programs in your Web browser and visualize what the computer is doing step-by-step as it executes those programs. So far, over 1.5 million people in over 180 countries have used Python Tutor to visualize over 15 million pieces of code, often as a supplement to textbooks, lecture notes, and online programming tutorials.

This tool was created by Philip Guo in January 2010. See project history.

All documentation is viewable online at: https://github.com/pgbovine/OnlinePythonTutor/tree/master/v3/docs

By far the most preferred way to use Python Tutor is via the official website: http://pythontutor.com/

You can use iframe embedding to quickly embed visualizations on your webpage.

It can be hard to run your own version locally for non-Python languages, since there are complex Docker-related details in v4-cokapi/ that I haven't yet cleanly packaged up.

To run Python visualizations on localhost:

pip install bottle # make sure the bottle webserver (http://bottlepy.org/) is installed
cd OnlinePythonTutor/v3/
python bottle_server.py

You should see the visualizer at: http://localhost:8003/visualize.html

... and the live programming environment at: http://localhost:8003/live.html

For further directions, see Overview for Developers or explore the rest of the docs.

For code or security contributions

• John DeNero - for helping with the official Python 3 port and lots of code patches
• Chris Horne - https://github.com/lahwran - for security tips
• Joshua Landau - joshua@landau.ws - for security tips
• David Wyde - https://davidwyde.com/ - for security tips
• Peter Wentworth and his students - for working on the original Python 3 fork circa 2010/2011
• Brad Miller - for adding pop-up question dialogs to visualizations, and other bug fixes
• David Pritchard and Will Gwozdz - for the Java visualizer and other frontend enhancements
• Peter Robinson - for v3/make_visualizations.py
• Chris Meyers - for custom visualizations such as v3/matrix.py and v3/htmlFrame.py
• Irene Chen - for holistic visualization mode -- v3/js/holistic.js

For general advice and feedback about this project:

• Ned Batchelder
• Jennifer Campbell
• John Dalbey
• John DeNero
• Fredo Durand
• Michael Ernst
• David Evans
• Paul Gries
• Mark Guzdial
• Adam Hartz
• Sean Lip
• Tomas Lozano-Perez
• Bertram Ludaescher
• Brad Miller
• Rob Miller
• Peter Norvig
• Andrew Petersen
• David Pritchard
• Suzanne Rivoire
• Guido van Rossum
• Peter Wentworth
• David Wilkins

... and many, many more!