Can I use mix / hex packages?

No network in the sandbox — mix compiles single files fine, but external hex deps cannot be fetched.

Yes, within a single script; supervision trees and Task work as normal.

Elixir · online compiler

Run Elixir online

Run Elixir online — Erlang VM, actor concurrency, browser-hosted.

Available versions

Firecracker microVM live per-test verdicts multi-file compile

Elixir is a modern functional language on the Erlang VM (BEAM). Small syntax over decades-proven concurrency: lightweight processes, message passing, supervision trees. Powering WhatsApp-scale services in production.

ls-judge runs Elixir with the standard `elixir` CLI inside a Firecracker microVM.

Starter code

What you get in Elixir

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

elixir

Elixir 1.18

n = IO.read(:stdio, :line) |> String.trim() |> String.to_integer()
IO.puts(n * 2)

stdin →

expected →

FAQ

Common questions about Elixir on ls-judge

Which Elixir version?: Elixir 1.x on OTP 26+.
Can I use mix / hex packages?: No network in the sandbox — mix compiles single files fine, but external hex deps cannot be fetched.
Does GenServer work?: Yes, within a single script; supervision trees and Task work as normal.
Free?: Yes.