Julia 1.x — the current stable major line.

Are packages preloaded?

Only Base and standard-library modules. Pkg.add cannot fetch external packages.

Why is the first run slow?

Julia's JIT warms up on first call. That is the "time-to-first-plot" problem — subsequent runs are fast.

Julia · online compiler

Run Julia online

Run Julia 1 online — scientific computing, browser-hosted.

Available versions

Julia 1.11 Julia 1

Firecracker microVM live per-test verdicts multi-file compile

Julia was built for scientific computing without the "two-language" problem: as fast as C, as expressive as Python, native multi-dispatch, and first-class arrays.

ls-judge runs Julia 1.x inside a Firecracker microVM. Cold-lane compilation costs a few seconds on the first run — that is the JIT warming up.

Starter code

What you get in Julia

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

julia

Julia 1.11

n = parse(Int, readline())
println(n * 2)

stdin →

expected →

FAQ

Common questions about Julia on ls-judge

Which Julia version?: Julia 1.x — the current stable major line.
Are packages preloaded?: Only Base and standard-library modules. Pkg.add cannot fetch external packages.
Why is the first run slow?: Julia's JIT warms up on first call. That is the "time-to-first-plot" problem — subsequent runs are fast.
Free?: Yes.