Online compiler

Erlang online compiler

Write Erlang (OTP 29) code below and run it, with input, in a sandbox on our servers. No sign-in, no ads. The same compiler is an API and an embeddable editor, for running Erlang in your own app, course or docs.

By the OnlineCompiler.io team. Updated .

What runs your code

VersionErlang OTP 29
Compiled withNo separate step: the run command compiles or interprets it
Run witherl -noshell -boot no_dot_erlang -pa /runcode -run runcode_erlang main code.erl
Limits30 seconds, 512 MB of memory, 2 CPUs, 64 KB of output per stream, no network
Typical run1.41 s, and 1.81 s for the slowest 1 in 20 (how we measured)

Good to know

  • Runs as an escript would: execution starts at main/1, and the -module and -export lines are optional.
  • io:get_line("") reads the next line of the Input tab, and io:fread("", "~d") reads numbers.
  • Compiler warnings, such as an unused variable, go to stderr, so they don't mix with the output. An uncaught exception exits with code 127.

Run Erlang 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.

Terminal
curl -X POST https://api.onlinecompiler.io/api/run-code-sync/ \
  -H "Authorization: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "compiler": "erlang-29",
    "code": "main(_) ->\n    Name = string:trim(io:get_line(\"\")),\n    io:format(\"Hello, ~s!~n\", [Name]).",
    "input": "Ada"
  }'

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

Put a runnable Erlang 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:

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

<div class="runcode" data-key="YOUR_WIDGET_KEY" data-lang="erlang-29">
  <script type="text/plain">
    main(_) ->
        Name = string:trim(io:get_line("")),
        io:format("Hello, ~s!~n", [Name]).
  </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, Elixir, Prolog, D, FreeBASIC, Dart, Clojure, Groovy, Scala, Zig, Nim, Crystal, Ada, PowerShell, Racket, Objective-C.

Frequently asked questions

Is this Erlang online compiler free?

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

Erlang/OTP 29's standard applications, including stdlib and crypto. Hex packages 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.