Zed-King Institute

    Online Python Compiler

    Write & Run Practice Examples

    Output

    Press Run (or Ctrl + Enter) — the output appears here. If your program asks for input(), type it here.

    Write and run real Python 3 programs — with interactive input(), NumPy, pandas and matplotlib — right here. Made for NIELIT O Level (M3 & PR-3), CCC and school students.

    Practice Questions — PythonA new question every time, checked instantly. Easy, medium and hard levels.

    How to Use This Online Python Compiler

    1. Type your program in the dark editor, or pick one from Examples.
    2. If your program uses input(), the question appears in the Output terminal — type your answer there and press Enter.
    3. Press Run (or Ctrl + Enter). The first run takes a few seconds while Python loads; after that it is instant.
    4. Read the result in Output. Errors appear there too, with the line number that caused them.
    5. Use Share code to send your program to a friend or teacher on WhatsApp — the link opens with your code already in the editor.

    What You Can Practice Here

    Everything in the NIELIT O Level M3-R5.1 (Programming and Problem Solving through Python) syllabus runs here: variables and operators, if/elif/else, for and while loops, strings and slicing, lists, tuples, sets, dictionaries, functions and recursion, exception handling with try/except, classes, and NumPy arrays.

    The examples above are the kind of programs asked in the PR-3 practical exam — prime numbers, factorial, Fibonacci series, patterns, palindromes, list statistics, character counting and NumPy matrix operations. Change the numbers, break the program on purpose, and read the error: that is the fastest way to learn.

    Online NumPy Compiler — Run NumPy Code Without Installing Anything

    This is also an online NumPy compiler. Write import numpy as np at the top of your program and press Run — NumPy is downloaded into your browser the first time, which takes a few seconds, and every run after that is instant. There is no pip install and nothing to set up on your computer or phone.

    Arrays, np.arange(), reshape(), slicing, np.dot() for matrix multiplication, transpose with .T, and sum(), mean(), max() and min() all work, because it is the real NumPy library and not a copy. To start from working code, open Examples and choose NumPy: array and matrix operations. pandas and matplotlib load the same way — a matplotlib chart is shown as a picture under your output.

    Why Your Code Is Safe and Private

    This compiler does not send your code anywhere. Python itself is downloaded into your browser and runs there, inside a separate worker, so a mistake such as an endless loop cannot freeze the page — it is simply stopped after 15 seconds. Your last program is remembered on this device, so you can close the tab and continue later.

    Frequently Asked Questions

    Is this online Python compiler free?

    Yes, completely free, with no login and no limit on how many programs you run. The Python interpreter runs inside your own browser, so your code is never sent to a server.

    Which Python version does it run?

    It runs real CPython 3 compiled to WebAssembly (Pyodide), not a simplified imitation. Standard Python syntax, functions, classes, lists, dictionaries, strings, exceptions and most of the standard library work exactly as they do on a computer.

    How do I use input() in this compiler?

    Just press Run. When your program reaches input(), the question appears in the Output terminal with a box after it — type your answer there and press Enter, exactly like Python on a computer.

    Can I use NumPy, pandas or matplotlib?

    Yes. Write import numpy as np (or pandas, matplotlib) and press Run — the library is downloaded the first time, which takes a few seconds, and after that it is instant. matplotlib charts appear as a picture under your output. Other pure-Python packages are installed from PyPI automatically. NumPy is part of the NIELIT O Level M3-R5.1 (Python) syllabus.

    What does not work?

    Programs that open a window (turtle, tkinter), read or write files on your computer, or connect to the internet will not work, because everything runs safely inside the browser. Packages that need compiled code not built for the browser cannot be installed either — the output tells you when that happens. A program that runs for more than 15 seconds is stopped, which protects you from endless loops.

    Is this useful for the O Level PR-3 practical exam?

    Yes. It is the same Python engine used in our free O Level PR-3 practical mock test, so you can write and check every practical program here and then attempt a timed paper when you are ready.

    Does it work on a mobile phone?

    Yes. It works in Chrome on Android and Safari on iPhone. The first run takes a little longer on mobile data because Python is downloaded once.