COBOL online compiler

What runs your code

Good to know

• Compiles with GnuCOBOL 3.2 (cobc -x) in free format, so code can start in column 1.
• For fixed-format code, with * comments in column 7, make >>SOURCE FORMAT IS FIXED the first line.
• ACCEPT reads the next line of the Input tab, and STOP RUN RETURNING 3 ends with exit status 3.

Run COBOL from your own code

Send the code and its input to the sync endpoint with an API key, and the output comes back in the response. The API docs cover the async endpoint with callbacks and every response field.

curl -X POST https://api.onlinecompiler.io/api/run-code-sync/ \
  -H "Authorization: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "compiler": "gnucobol-3.2",
    "code": "IDENTIFICATION DIVISION.\nPROGRAM-ID. HELLO.\nDATA DIVISION.\nWORKING-STORAGE SECTION.\n01 NAME PIC X(64).\nPROCEDURE DIVISION.\n    ACCEPT NAME\n    DISPLAY \"Hello, \" FUNCTION TRIM(NAME) \"!\"\n    STOP RUN.",
    "input": "Ada"
  }'

The response has output ("Hello, Ada!\n" here), error, exit_code, time and memory.

Put a runnable COBOL example on your site

The editor above is the embeddable widget. Add the script and a div with your widget key, and your readers can edit and run the code without an account:

<script src="https://onlinecompiler.io/widget.js"></script>

<div class="runcode" data-key="YOUR_WIDGET_KEY" data-lang="gnucobol-3.2">
  <script type="text/plain">
    IDENTIFICATION DIVISION.
    PROGRAM-ID. HELLO.
    DATA DIVISION.
    WORKING-STORAGE SECTION.
    01 NAME PIC X(64).
    PROCEDURE DIVISION.
        ACCEPT NAME
        DISPLAY "Hello, " FUNCTION TRIM(NAME) "!"
        STOP RUN.
  </script>
</div>

On a platform that takes an iframe but not a script, such as many course sites, use the iframe embed. For Docusaurus, MkDocs, Sphinx and Mintlify, see runnable code examples in docs.

Other languages

Python, C, C++, Java, C#, F#, Go, Rust, PHP, Ruby, Haskell, TypeScript, JavaScript, SQL, Bash, Fortran, Visual Basic, Kotlin, R, Swift, Perl, Julia, Pascal, Octave, Assembly, Lua, OCaml, Common Lisp, Erlang, Elixir, Prolog, D, FreeBASIC, Dart, Clojure, Groovy, Scala, Zig, Nim, Crystal, Ada, PowerShell, Racket, Objective-C.

Frequently asked questions

Is this COBOL online compiler free?

Yes. Running COBOL on this page needs no account and shows no ads. To run COBOL from your own app or site, the API and the widget are free up to 100,000 runs a month, commercial use included.

Can my COBOL program read input?

Yes. Type it in the Input tab before you run, and the program reads it from standard input. The whole input is sent when you press Run, so a program can't ask for more while it runs.

Can I use COBOL libraries?

GnuCOBOL's runtime and intrinsic functions, such as <code>FUNCTION TRIM</code> and <code>FUNCTION NUMVAL</code>. Other libraries can't be installed, and programs have no network access.

How long can a program run?

Up to 30 seconds, with 512 MB of memory and 2 CPUs. A program still running at 30 seconds is stopped with exit code 124, and output over 64 KB per stream is cut.

Where does my code run?

On our servers, in a fresh gVisor sandbox with no network access that is deleted when the run ends. Each run is kept in execution history with its output; the security page says what is stored.