Can I run COBOL online without installing it?

Yes. CompileBytes compiles and runs your COBOL code in an isolated hosted runtime, so you do not need a mainframe or a local compiler.

Which COBOL compiler and version does CompileBytes run?

It uses GnuCOBOL reported as version 3.1.2, an open-source compiler that supports standard COBOL.

Can I provide input via stdin?

Yes. Use the ACCEPT statement to read a value into a variable, and supply the data through the input box.

Yes, it is completely free, and GnuCOBOL is open-source software released under the GNU GPL and LGPL.

Why does COBOL care about column positions?

Traditional fixed-format COBOL reserves columns 8-11 (Area A) and 12-72 (Area B) for code, so division headers and paragraphs begin in Area A while statements sit in Area B.

Online COBOL Compiler & Editor

main.cob

Tap Run to execute

main.cob · output appears here

main.cob

Press Run to execute

Output streams here as your program runs.

COBOL 3.1.2Readymain.cobLn 1, Col 1Spaces: 4UTF-8

About the COBOL playground

COBOL (Common Business-Oriented Language) is one of the oldest programming languages, designed in 1959 by a committee that included pioneer Grace Hopper. It was built for business, finance, and administrative systems, with an English-like, verbose syntax intended to be readable by non-programmers. COBOL programs are organized into divisions and excel at processing large volumes of records, fixed-format data, and precise decimal arithmetic.

On CompileBytes, COBOL is compiled with GnuCOBOL, reported as version 3.1.2, an open-source compiler that translates COBOL into C and then to native code. Despite its age, COBOL still runs an enormous share of mainframe banking, insurance, and government workloads worldwide. Its structured divisions, the PERFORM statement, and powerful PICTURE clauses for formatting data make it well suited to reliable, long-lived transaction processing.

3.1.2COBOL runtime

main.cobentry file

single fileworkspace

stdinprogram input

How it works

Write

main.cob is the entry point for each run.

Give it input

Use the Input panel to pipe standard input to your program when it needs data.

Run

Run sends your code to a fresh hosted runtime and streams the result into the output panel.

Keep or share

Your draft stays in this browser, and Share creates a separate snapshot link.

Hello, World!

       IDENTIFICATION DIVISION.
       PROGRAM-ID. HELLO.
       PROCEDURE DIVISION.
           DISPLAY 'Hello, World!'.
           STOP RUN.

Variables and arithmetic

       IDENTIFICATION DIVISION.
       PROGRAM-ID. ADD-NUMS.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 A PIC 9(3) VALUE 10.
       01 B PIC 9(3) VALUE 20.
       01 C PIC 9(4).
       PROCEDURE DIVISION.
           ADD A B GIVING C.
           DISPLAY 'Sum: ' C.
           STOP RUN.

Loop with PERFORM

       IDENTIFICATION DIVISION.
       PROGRAM-ID. COUNTER.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 I PIC 9(2).
       PROCEDURE DIVISION.
           PERFORM VARYING I FROM 1 BY 1 UNTIL I > 5
               DISPLAY 'Count: ' I
           END-PERFORM.
           STOP RUN.

Reading input

       IDENTIFICATION DIVISION.
       PROGRAM-ID. GREET.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 NAME-IN PIC X(20).
       PROCEDURE DIVISION.
           DISPLAY 'Enter name: '.
           ACCEPT NAME-IN.
           DISPLAY 'Hello, ' NAME-IN.
           STOP RUN.

Conditional with IF

       IDENTIFICATION DIVISION.
       PROGRAM-ID. CHECK.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 N PIC 9(3) VALUE 42.
       PROCEDURE DIVISION.
           IF N > 40
               DISPLAY 'Big'
           ELSE
               DISPLAY 'Small'
           END-IF.
           STOP RUN.

Calling a paragraph

       IDENTIFICATION DIVISION.
       PROGRAM-ID. PARAS.
       PROCEDURE DIVISION.
       MAIN-PARA.
           DISPLAY 'Start'.
           PERFORM GREET-PARA.
           DISPLAY 'End'.
           STOP RUN.
       GREET-PARA.
           DISPLAY 'Hello from paragraph'.

COMPUTE arithmetic

       IDENTIFICATION DIVISION.
       PROGRAM-ID. AREA.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 W PIC 9(3) VALUE 4.
       01 H PIC 9(3) VALUE 5.
       01 RESULT-VAL PIC 9(5).
       PROCEDURE DIVISION.
           COMPUTE RESULT-VAL = W * H.
           DISPLAY 'Area: ' RESULT-VAL.
           STOP RUN.

EVALUATE (case)

       IDENTIFICATION DIVISION.
       PROGRAM-ID. PICKER.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 N PIC 9 VALUE 2.
       PROCEDURE DIVISION.
           EVALUATE N
               WHEN 1 DISPLAY 'one'
               WHEN 2 DISPLAY 'two'
               WHEN OTHER DISPLAY 'many'
           END-EVALUATE.
           STOP RUN.

Table (array) with OCCURS

       IDENTIFICATION DIVISION.
       PROGRAM-ID. TABLES.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 NUMS.
          05 N PIC 9(2) OCCURS 5 TIMES.
       01 I PIC 9(2).
       01 TOTAL PIC 9(4) VALUE 0.
       PROCEDURE DIVISION.
           PERFORM VARYING I FROM 1 BY 1 UNTIL I > 5
               MOVE I TO N(I)
               ADD N(I) TO TOTAL
           END-PERFORM.
           DISPLAY 'Total: ' TOTAL.
           STOP RUN.

Editor guide

The editor uses Monaco, the engine behind VS Code, with language-aware editing tools and familiar keyboard controls.

Getting started

Type or paste your code into the editor, then click Run (or press Ctrl/Cmd + Enter) to execute it.

Output streams into the console panel, including runtime errors, exit status, and execution time.

Nothing to install and no account to create — code runs in an isolated hosted runtime.

A full-featured code editor

Language-aware autocomplete and IntelliSense suggestions where the editor has a matching language service

Syntax highlighting, with native compiler and runtime errors shown in the console

Bracket matching, auto-indentation, code folding, and a minimap

Multi-cursor editing plus find & replace (Ctrl/Cmd + F)

Full undo/redo history and copy to clipboard

Built on Monaco — the same editor that powers VS Code

Running & testing your code

Run on demand, or turn on Auto-run to execute on every change

Stop long-running or infinite programs at any time

A real console shows standard output, errors, exit status, and execution time

Program input

Pass standard input (stdin) to your program from the Input panel — one value per line

Make it yours

Switch between light and dark themes

Adjust font size and other editor settings

Toggle side-by-side or top/bottom layouts

Enter distraction-free fullscreen mode

Share & save

Generate a shareable link to your exact code in one click — no login needed

Your work autosaves to your browser, so you can pick up where you left off

Copy the active file to your clipboard

Handy keyboard shortcuts

Run code: Ctrl/Cmd + Enter

Find & replace: Ctrl/Cmd + F

Open the full shortcut list from the keyboard icon in the toolbar

COBOL single-file scratchpad

COBOL is one of 46 single-file compiler scratchpads. Each run submits only main.cob; local sibling-file imports are not enabled.

Linked-project languages (23): Node.js, TypeScript, Deno, Python, C, Go, Dart, Swift, Rust, Ruby, PHP, Java, Kotlin, C++, C#, Nim, Crystal, Haxe, Zig, Scala, D, Bun, Objective-C.

Single-file scratchpads (46): Matplotlib, NumPy, pandas, Haskell, Clojure, Perl, Lua, Tcl, jq, Raku, Elixir, Bash, Zsh, Nushell, R, Assembly (NASM), Julia, Octave, Groovy, PowerShell, Visual Basic .NET, Odin, Pascal, Lisp, Erlang, CoffeeScript, COBOL, BASIC, V, Racket, OCaml, Prolog, AWK, Emacs Lisp, Emojicode, Forth, F#, Fortran, Assembly (NASM64), Solidity, Mojo, Ada, WASM (WAT), Gleam, Shell Script (sh), Scheme.

Download

Download file exports the active COBOL source file.

Every shortcut, searchable:

COBOL

COBOL Playground

Write

Give it input

Run

Keep or share

Run

Editing

Navigation

Selection

Terminal