Online compilers

Write and run code in C, C++, Python, JavaScript, TypeScript, R, PHP, Ruby, Lua, SQL, Prolog, Scheme, Clojure and CoffeeScript, free, instantly and privately. Every compiler runs in your browser using WebAssembly, so your code never leaves your device.

Online Python CompilerFree online Python compiler: write and run Python 3.12 code in your browser with input(), the standard library and auto-loaded packages like NumPy and pandas.
Online JavaScript CompilerFree online JavaScript compiler and playground: run modern JS with async/await and see console output instantly, sandboxed in your browser.
Online TypeScript CompilerFree online TypeScript compiler: transpile TypeScript 5.6 to JavaScript, see the generated code and run it instantly in your browser.
Online PHP CompilerFree online PHP compiler: run PHP 8 code with a real PHP interpreter compiled to WebAssembly. Test functions, arrays, JSON and string handling instantly.
Online Ruby CompilerFree online Ruby compiler: run Ruby 3.3 code with the standard library using the official ruby.wasm build, right in your browser.
Online Lua CompilerFree online Lua compiler: run Lua 5.4 scripts instantly with a WebAssembly build of the official interpreter. Perfect for learning and testing.
Online SQL CompilerFree online SQL compiler: create tables, insert data and run SQL queries against a real SQLite database in your browser, with results as tables.
Online C CompilerFree online C compiler: write, compile and run C programs with a real Clang compiler running in your browser, with stdin input and warnings.
Online C++ CompilerFree online C++ compiler: compile and run C++20 programs with Clang in your browser, including the STL, iostream and stdin input. No sign-up.
Online R CompilerFree online R compiler: run R code with webR in your browser, including data frames, statistics, linear models and base graphics plots.
Online Prolog CompilerFree online Prolog compiler: run SWI-Prolog programs in your browser with facts, rules, recursion and formatted output. Nothing is uploaded.
Online Scheme InterpreterFree online Scheme interpreter: run Scheme and Lisp-style code with recursion, lambdas, lists and tail calls directly in your browser.
Online Clojure CompilerFree online Clojure compiler: run Clojure code with maps, vectors, lazy sequences and threading macros in your browser via the Small Clojure Interpreter.
Online CoffeeScript CompilerFree online CoffeeScript compiler: compile CoffeeScript 2 to JavaScript, view the generated code and run it instantly in your browser.

How our online compilers work

Traditional online compilers send your code to a remote server, run it there and send the output back. Ours take a different approach: the language runtime itself (CPython, R, SWI-Prolog, the Ruby interpreter, PHP, Lua or SQLite compiled to WebAssembly, a complete Clang/LLVM toolchain that compiles C and C++ to WebAssembly, or your browser's own JavaScript engine) is downloaded once and runs inside a sandboxed Web Worker in your browser. That means instant re-runs, no queue, no account, and complete privacy: the code you write is never uploaded or stored on our servers.

What you can do

  • Learn a language and experiment with examples.
  • Test snippets, algorithms and regular expressions before using them in a project.
  • Practise SQL against a real SQLite database.
  • Teach and demo code without asking students to install anything.

Limitations

Because everything runs in a browser sandbox, programs cannot open network sockets, access your files or install system packages, and each run is limited by the time limit you choose. Compiled languages such as Java, C#, Go, Rust and C/C++ need a different kind of runtime and are coming later.

Looking for formatters instead? See all developer tools, including the JSON formatter and SQL formatter.

Copied to clipboard