Run Python 3.13 online

What's in Python 3.13

• PEP 703 free-threaded build behind --disable-gil (experimental, opt-in).
• PEP 744 tier-2 JIT compiler shipping in binaries built with --enable-experimental-jit.
• New REPL with multi-line editing, colour, and paste mode — a huge day-to-day improvement.

What you get in Python 3.13

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

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

How ls-judge runs Python 3.13

Every submission is compiled and executed inside its own Firecracker microVM — the same isolation primitive AWS Lambda uses. No shared container, no shared kernel with other users' code. The Python 3.13toolchain shipped with the microVM is the real thing (not a browser-side emulation): syscalls behave the way they do in production, and the compile / runtime behaviour matches what you would see on your own machine with that version installed.

Feed stdin from the Tests panel, watch verdicts stream per test case over a WebSocket. Free to use, no sign-up, works from any browser.