Free Online Python Tutor & Code Visualizer

Visualize Python, JavaScript, Java, and C++ code execution step-by-step with variable tracking.

Powered by Python Tutor

This tool integrates the official Python Tutor by Philip Guo - the world's most popular program visualization tool, used by over 20 million people in 180+ countries. It provides step-by-step visual debugging for Python, JavaScript, Java, C, and C++.

Real code execution

Visual memory diagrams

5 programming languages

AI tutor assistance

Visit pythontutor.com for more information and documentation.

Select Programming Language

Quick Start Examples

Click any example below to load it into the visualizer and see how it executes step-by-step:

Python Tutor Visualizer

- Step-by-step execution

How to Use Python Tutor

Getting Started

Select your programming language above
Click a quick example or write your own code
Click "Visualize Execution" in the visualizer
Use navigation buttons to step through execution
Watch variables and memory change in real-time

Features

Visual memory diagrams with objects and pointers
Heap and stack visualization
Step-by-step code execution
AI tutor for help and explanations
Share visualizations via URL

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How to Use

Step-by-step guide 3 steps

1 Paste Python Code: Input the snippet of Python code you want to analyze.
2 Visualize Execution: Click "Visualize Execution" to start the step-by-step process.
3 Trace Changes: Use the navigation controls to step forward/backward, watching how variables, memory, and function calls change. Visualize Python code now!

FAQ

Common questions 3 questions

Why is it called a "Tutor"?

Because it visually explains the program's execution flow, making it an invaluable tool for beginners to understand memory and scope.

Can it debug large programs?

It is best suited for small to medium-sized code snippets (loops, functions, class methods) to maintain clarity.

Which Python version is supported?

Typically supports Python 3, but you should verify the exact supported version in the tool's settings.

Use Cases & Examples

Real-world applications 3 examples

Learning

Clearly understand complex concepts like recursion, object instantiation, and how lists/dictionaries are stored in memory.

Teaching

Use the Python debugging tool in lectures to show students exactly what the interpreter is doing line by line.

Debugging

Track down subtle bugs related to variable scoping or list mutation by examining the precise state changes.