Online Compiler, AI Tutor, and Visual Debugger for Python, Java, C, C++, and JavaScript

Python Tutor helps you do programming homework assignments in Python, Java, C, C++, and JavaScript. It contains a step-by-step visual debugger and AI tutor to help you understand and debug code.

Start coding online in Python, Java, C, C++, and JavaScript

Since 2010, over 20 million people in more than 180 countries have used Python Tutor to visualize over 300 million pieces of code. It is the most widely-used program visualization tool for CS education.

As a preview, here is a small example that visualizes recursion in Python:

Python 3.6

	1	def listSum(numbers):
	2	if not numbers:
	3	return 0
	4	else:
	5	(f, rest) = numbers
	6	return f + listSum(rest)
	7
	8	myList = (1, (2, (3, None)))
	9	total = listSum(myList)

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line that just executed
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Step 11 of 22

Visualized with pythontutor.com

Frames

Global frame

listSum
myList

listSum

numbers
f	1
rest

listSum

numbers
f	2
rest

Objects

function

listSum(numbers)

tuple

0	1
1

tuple

0	1
2

tuple

0	1
3	None

You can also ask an AI tutor for help in understanding your code and visualization:

Here are some examples of how this tool visualizes Java, C, and C++ code: