Is PyRun completely free to use?

Yes — PyRun is entirely free. There is no sign-up, no subscription, and no hidden limit. You can write and run Python code as many times as you like without creating an account.

Does PyRun work without an internet connection?

After the first load, PyRun continues to work offline. The Python engine (Pyodide) is cached locally by your browser, so you can keep coding even when you have no internet access. Some features like link sharing require a connection.

Which version of Python does PyRun use?

PyRun runs Python 3.11 via Pyodide, a port of CPython compiled to WebAssembly. You get access to the full Python standard library, including modules like math, json, datetime, itertools, and more.

Is my code private? Does PyRun store what I write?

Your code never leaves your device unless you explicitly generate a public share link. All execution happens entirely inside your browser sandbox. PyRun has no server that receives or stores your code.

Can I use PyRun on a phone or tablet?

Yes. PyRun is built with a responsive layout and works on mobile browsers. The interface adapts to smaller screens, switching to a stacked layout so both the editor and output terminal remain accessible.

Can I import and open my own Python files?

Absolutely. You can open any .py file from your device using the toolbar button or with the Ctrl+O keyboard shortcut. The file loads directly into the editor, ready to run.

How do I share my code with someone else?

Use the Share button in the toolbar or press Ctrl+H. PyRun generates a unique URL that encodes your code. Anyone with the link can open it in their browser and see (or run) the exact same code.

Does PyRun support the input() function?

Yes. PyRun has full support for Python's built-in input() function. When your code reaches an input() call, the terminal prompts you to type a response, just as it would in a local terminal.

regex

Parsing

Advanced regex engine

Try regex in PyRun

What is regex?

The regex module is a drop-in replacement for Python's built-in re module, offering additional features including fuzzy matching (approximate string matching), variable-width lookbehinds, named capture groups with repeated captures, POSIX character classes, and atomic grouping.

regex is available in PyRun via micropip. It's particularly useful when you need to match patterns with slight typos (fuzzy matching), work with complex Unicode text, or use regex features that aren't supported in the standard re module.

Code Example

Named capture groups and fuzzy pattern matching.

Regex: Named Groups & Fuzzy

Try in Editor

import regex

# Named capture groups — parse a log line
log = "2025-07-04 14:32:01 ERROR [auth] Login failed for user@example.com"
pattern = r"(?P<date>\d{4}-\d{2}-\d{2}) (?P<time>\d{2}:\d{2}:\d{2}) (?P<level>\w+) \[(?P<module>\w+)\] (?P<message>.+)"
m = regex.match(pattern, log)
if m:
    for k, v in m.groupdict().items():
        print(f"  {k:<10}: {v}")

# Fuzzy matching — find 'colour' with up to 1 error
print("\nFuzzy search (≤1 substitution):")
text = "I prefer colour and cilor and colouur"
for hit in regex.finditer(r"(?:colour){s<=1}", text):
    print(f"  found '{hit.group()}' at {hit.span()}")

Why run regex in PyRun?

✦ Zero setup — no pip install, no virtual environment, no Python download
✦ Instant results — powered by WebAssembly, runs locally in your browser
✦ Share your code — generate a link and anyone can run it instantly
✦ Works offline — after first load, PyRun runs without internet

Open editor with regex example

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