$ python-online-compiler --mode=debug

Master Python with Tricky Coding Puzzles & Practice Questions

PyDebug throws you real broken Python code and tricky output-prediction puzzles β€” solved right in your browser, no separate compiler tab needed.

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Today’s challenge

Finding today’s Python puzzle…

Take challenge
def total(items):
    total = 0
    for i in range(1, len(items)):
        total += items[i]
    return total
# IndexError risk β€” off-by-one bug. Can you spot it?

Fix the Bug

Broken code, real errors. Edit it in the playground until it runs clean.

Predict the Output

Read tricky Python snippets and guess exactly what they print β€” no running allowed.

Built-in Playground

Python runs directly in your browser. No installs, no other compiler websites.

Free + Premium

Solid free library to start, deeper premium problem sets when you're ready to go further.

Ten minutes a day beats a weekend cram

One bug, one prediction, one small win β€” that's all it takes to build a real Python habit. PyDebug tracks your streak and XP so you can see your consistency add up day by day, and picks up right where you left off.

Daily streak tracking
XP for every problem solved
Leaderboard to stay motivated

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Python Online Compiler – Frequently Asked Questions

Everything you need to know about running Python code online with PyDebug's free browser-based compiler.

Is the PyDebug Python online compiler really free?

Yes. PyDebug's online Python compiler is completely free to use. You can write, run, and test Python code directly in your browser without installing anything or paying a fee. No credit card is required for the compiler or the practice problems.

Do I need to install Python to use this compiler?

No installation is needed. The compiler runs Python right inside your browser using WebAssembly (Pyodide), so it works on Windows, macOS, Linux, Chromebooks, and mobile devices. You simply open the page and start coding.

How do I run my first Python program?

Open the Playground, type your code in the editor β€” for example print("Hello, PyDebug!") β€” and click the Run Code button. The output appears instantly in the output panel. You can also open files, save snippets, and reset the editor whenever you need.

Can I practice debugging and output prediction too?

Yes. Besides the compiler, PyDebug offers bug-fixing challenges where you repair broken code, and output-prediction questions where you guess what a snippet prints. Both formats sharpen the exact skills interviewers test.

Do I need an account to use the compiler?

No. Anyone can open the Playground and run code without signing up. Creating a free account adds extras such as unlimited daily solves, saved progress, XP, streaks, and the leaderboard β€” but the core compiler always stays free.

Is my code saved anywhere?

In the Playground, your files are saved when you click Save. Code you run as a guest stays on your device; once you log in, your progress and saved files follow your account.

Which Python topics can I practice on PyDebug?

You can practice everything from beginner basics to advanced topics: variables, data types, loops, functions, lists, dictionaries, sets, tuples, OOP, recursion, exceptions, sorting, and generators. Browse the free Python tutorials for step-by-step explanations.