Run Smalltalk online

Run Smalltalk online — the mother of OO, browser-hosted.

Version

Firecracker microVM live per-test verdicts multi-file compile

Smalltalk defined object-oriented programming: everything is an object, everything is a message send. Kay, Ingalls, and the Xerox PARC crew invented the entire modern OO vocabulary here.

Starter code

What you get in Smalltalk

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

smalltalk

Smalltalk 0

| n |
n := stdin nextLine asInteger.
Transcript show: (n * 2) printString; nl.

stdin →

expected →

FAQ

Common questions about Smalltalk on ls-judge

Which Smalltalk?: GNU Smalltalk.
Squeak / Pharo?: Those are image-based — bring your own image (unsupported on the free tier).
Free?: Yes.
Entry filename?: main.st.