Swift online compiler

What runs your code

Good to know

• Compiles with swiftc -O, so a program is top-level code with no main function.
• readLine() reads the next line of the Input tab and returns nil at the end.
• Checks such as array bounds and integer overflow stay on. A failed check stops the program with exit code 132 and a crash report that points at the line; output printed just before it can be lost.

Run Swift 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": "swift-6.4",
    "code": "let name = readLine() ?? \"\"\nprint(\"Hello, \\(name)!\")",
    "input": "Ada"
  }'

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

Put a runnable Swift 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="swift-6.4">
  <script type="text/plain">
    let name = readLine() ?? ""
    print("Hello, \(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, COBOL, 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 Swift online compiler free?

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

The Swift standard library, Foundation (<code>import Foundation</code>) and Glibc. Swift packages can't be added, 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.