Typically 4-10× faster on pure-Python compute; slower on short scripts (JIT warmup cost).

Are numpy / pandas available?

No — cpyext support of numpy is fragile and not enabled here.

Algorithmic contest code with heavy loops; use CPython (/lang/python) for scripts using scientific libraries.

PyPy · online compiler

Run PyPy online

Run PyPy 3 online — Python-compatible JIT, faster than CPython.

Available versions

PyPy 3.11 PyPy 3

Firecracker microVM live per-test verdicts multi-file compile

PyPy is a Python implementation with a tracing JIT — usually 4-10x faster than CPython on pure Python code. Full Python 3 compatibility; some C extensions fail to compile against its cpyext but most pure-Python code just works.

ls-judge runs PyPy 3.x inside a Firecracker microVM.

Starter code

What you get in PyPy

Clicking "Run now" opens the playground with this exact code and a matching test case pre-loaded — passes on first Run.

pypy

PyPy 3.11

n = int(input())
print(n * 2)

stdin →

expected →

FAQ

Common questions about PyPy on ls-judge

How fast vs CPython?: Typically 4-10× faster on pure-Python compute; slower on short scripts (JIT warmup cost).
Are numpy / pandas available?: No — cpyext support of numpy is fragile and not enabled here.
When to prefer PyPy?: Algorithmic contest code with heavy loops; use CPython (/lang/python) for scripts using scientific libraries.
Free?: Yes.