Run Go online — Go 1.22 through 1.25, real toolchain, no install.
Go is Google's pragmatic answer to backend engineering: fast compiles, garbage collection, a strong concurrency model (goroutines + channels), and a boring type system that gets out of the way. The most-used language for cloud infrastructure today.
ls-judge runs Go with the standard `go` tool inside a Firecracker microVM. Pick the version — from 1.22 through the latest 1.25 — and get the matching stdlib. Generics work. `go run` semantics.
Multi-file support: add files via the file panel and they compile together as `package main`. Stdin from Test cases maps to os.Stdin.
Because ls-judge itself is written in Go (behind a horizontally-scalable Firecracker fleet), the Go path is one of the most heavily tested runtimes here — dogfood.
Clicking "Run now" opens the playground with this exact code and a matching test case pre-loaded — passes on first Run.
package main
import "fmt"
func main(){var n int;fmt.Scan(&n);fmt.Println(n*2)}
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