Ruby · version 3

Run Ruby 3 online

Released Rolling (LTS-adjacent)

The generic Ruby 3.x runtime — a stable pick for teaching material.

Release

What's in Ruby 3

  • Full Ruby 3 syntax: pattern matching, one-line method defs, `rightward` assignment.
  • YJIT available; solid stdlib coverage; no network so pure Ruby only.
  • Same MRI as the point-version runtimes — code portable between them.
Starter code

What you get in Ruby 3

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

ruby
Ruby 3
n = gets.chomp.to_i
puts n * 2
stdin →21
expected →42
How it runs

How ls-judge runs Ruby 3

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 Ruby 3toolchain 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.

Other Ruby versions
Ruby 3.4Ruby 3.3Ruby 3.2all Ruby →