FreeBASIC online compiler

What runs your code

Good to know

• Compiles with FreeBASIC 1.10 in its default fb dialect; for QBasic code, make #lang "qb" the first line.
• Input and Line Input read the Input tab. Input prints no prompt, not even one you give it (Input "Age", n); Line Input "Name: ", s prints its prompt.
• Print puts a space before a positive number, as BASIC does; join values with & to avoid it.

Run FreeBASIC 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": "fbc-1.10",
    "code": "Dim userName As String\nLine Input userName\nPrint \"Hello, \" & userName & \"!\"",
    "input": "Ada"
  }'

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

Put a runnable FreeBASIC 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="fbc-1.10">
  <script type="text/plain">
    Dim userName As String
    Line Input userName
    Print "Hello, " & userName & "!"
  </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, COBOL, Perl, Julia, Pascal, Octave, Assembly, Lua, OCaml, Common Lisp, Erlang, Elixir, Prolog, D, Dart, Clojure, Groovy, Scala, Zig, Nim, Crystal, Ada, PowerShell, Racket, Objective-C.

Frequently asked questions

Is this FreeBASIC online compiler free?

Yes. Running FreeBASIC on this page needs no account and shows no ads. To run FreeBASIC 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 FreeBASIC 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 FreeBASIC libraries?

FreeBASIC's runtime library. There's no graphics library, so programs that use <code>Screen</code> fail to link, 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.