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.

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

The latest development version of the code is in v5-unity, although lots of legacy documentation still resides in v3.

• Unsupported features and known bugs
• Frequently Asked Questions
• Overview for Developers

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

Quick Start

BY FAR the most preferred way to use Python Tutor is via the official website, since it contains the latest updates: http://pythontutor.com/

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

If you want to run locally on your own computer, to run Python visualizations try:

pip install bottle # make sure the bottle webserver (http://bottlepy.org/) is installed
cd OnlinePythonTutor/v5-unity/
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

However, it can be hard to run your own visualizer locally for non-Python languages, since there are complex dependencies in v4-cokapi/ that I haven't yet cleanly packaged up. By default, the local version you run will call my own server to run the non-Python backends, so please be mindful of your bandwidth usage.

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

Acknowledgments

For code or security contributions:

• Irene Chen - experimental holistic visualization mode - v3/js/holistic.js
• John DeNero - helping with the official Python 3 port, bug fixes galore
• Mark Liffiton - localStorage bug fix
• Chris Meyers - custom visualizations such as v3/matrix.py and v3/htmlFrame.py
• Brad Miller - adding pop-up question dialogs to visualizations, other bug fixes
• David Pritchard and Will Gwozdz - Java visualizer and other frontend enhancements
• Peter Robinson - v3/make_visualizations.py
• Peter Wentworth and his students - working on the original Python 3 fork circa 2010-2011
• Security tips and vulnerability reports: Aaron E. (https://arinerron.com), Chris Horne (https://github.com/lahwran), Joshua Landau (joshua@landau.ws), David Wyde (https://davidwyde.com/)

For user testing and feedback from instructors' perspectives:

• Ned Batchelder
• Jennifer Campbell
• John Dalbey
• John DeNero
• Fredo Durand
• Michael Ernst
• David Evans
• Paul Gries
• Mark Guzdial
• Adam Hartz
• Sean Lip
• Fernando Perez
• 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!