Run Zig 0.13 online

What you get in Zig 0.13

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

const std = @import("std");
pub fn main() !void {
    const stdin = std.io.getStdIn().reader();
    const stdout = std.io.getStdOut().writer();
    var buf: [64]u8 = undefined;
    const line = try stdin.readUntilDelimiter(&buf, '\n');
    const n = try std.fmt.parseInt(i64, std.mem.trim(u8, line, &std.ascii.whitespace), 10);
    try stdout.print("{d}\n", .{n * 2});
}

How ls-judge runs Zig 0.13

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 Zig 0.13toolchain 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.