COBOL · version 3

Run COBOL 3 online

COBOL 3 — run it in a Firecracker microVM on ls-judge. Real toolchain, no wrapper.

Starter code

What you get in COBOL 3

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

cobol
COBOL 3
IDENTIFICATION DIVISION.
PROGRAM-ID. solution.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 N PIC 9(9).
01 R PIC 9(9).
PROCEDURE DIVISION.
    ACCEPT N
    COMPUTE R = N * 2
    DISPLAY R
    STOP RUN.
stdin →21
expected →000000042
How it runs

How ls-judge runs COBOL 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 COBOL 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 COBOL versions
COBOL 3.7all COBOL →