Cheerp - a C/C++ compiler for Web applications - generates WebAssembly and JavaScript
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Stefano De Rossi
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media Added new Cheerp logo to meta project. Nov 2, 2017 Updated with link to tutorial. Nov 14, 2017

Cheerp - a C/C++ compiler for Web applications

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Cheerp is an open-source, commercial C/C++ compiler for Web applications. It allows to compile virtually any C/C++ code (up to C++14) to WebAssembly, JavaScript, asm.js or a combination thereof.

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Main documentation link:

Main project link:

This repository is the main reference for documentation, issue tracking, and release notes. Please contribute to Cheerp!

What is Cheerp?

Cheerp is a C/C++ compiler for the Web, based and integrated into the LLVM/clang infrastructure, and featuring numerous custom optimisation steps to maximise performance and minimise size of the compiled JavaScript/WebAssembly output.

Cheerp is used mainly to port existing C/C++ libraries and applications to HTML5, but can also be used to write high-performance Web applications and components from scratch. C/C++ gets optimised and compiled into JavaScript/WebAssembly, and can easily be deployed as part of a web page.

What is unique about Cheerp?

Cheerp enables C/C++ code to be compiled to WebAssembly, JavaScript, asm.js or a combination thereof. Compared to alternative C/C++ compilers for web applications such as Emscripten, Cheerp:

  1. Achieves the same near-native runtime performance when compiling to WebAssembly, but can also compile to a JavaScript output with dynamic memory (garbage-collectible output), zero-overhead DOM manipulation and access to WebApis and superior C++-JavaScript interoperability.
  2. Allows to compile a single code base into a combination of WebAssembly and JavaScript by (optionally) tagging portions of the code with [[cheerp::genericjs]] and [[cheerp::wasm]].
  3. Can generate code 30-90% smaller than Emscripten, with faster startup.

Cheerp is open-source software and is free to use for GPLv2 projects. Non-copyleft commercial licenses, commercial support and consulting packages are available from Leaning Technologies.

Getting Started

You can download the latest official release of Cheerp for Windows, Linux and macOS a this address: Installation instructions are available here.

Alternatively, you can build Cheerp from source. Please follow the instructions available here.

To get started, you can have a look at our simple tutorial to build your first JavaScript Hello World, or your first WebAssembly program.

For a more in-depth tutorial, please visit this tutorial: a game of Pong in WebAssembly.

Bugs and Questions

You can get in touch with us using our Gitter chat, or by filing a bug on our Issue tracker.


Documentation is available at