Free tool
Visualize Python Code — Run It Step by Step
A free Python visualizer: type or paste Python code and run it step by step, one line at a time — see every variable change, every condition checked, and the flow chart light up as your program moves.
Your code runs safely inside your own browser. Code that opens real windows (tkinter, turtle, pygame) cannot run in a browser, so try code that prints text or does maths.
Variables & memory
Every variable appears as a box that updates the moment its value changes.
Decisions & loops
See each if and while check with real values, like 3 > 0 → TRUE.
Flow chart
A live flow chart shows which path your program takes, step by step.
How to run Python code step by step
- Pick an example above or paste your own Python code into the editor.
- If your code uses input(), add the values in the Input box, one per line.
- Click Visualize code to open the step-by-step view.
- Use Next, Previous and Play to move line by line and watch variables, output and the flow chart update.
Why visualize Python code?
Reading code tells you what it says; seeing it run shows you what it does. When you visualize Python code, you can watch each loop repeat, see which branch an if statement takes, and spot exactly where a value changes — the fastest way for beginners to understand and debug programs. Want guided practice? Try the free for loop and while loop lessons.
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