If you are reading this on GitHub, please visit the website. If your are on the website, here’s the source code.

Wasup is a build server and CDN for single-page, portable and standalone C programs. Given programs are compiled to Web Assembly, without any modules (such as libc).

You can use this for quick wasm experiments or rapid prototyping on a machine that doesn’t have wasm-llvm or emsdk installed. Don’t use this for anything serious.


This demo uses a modified version of migerh’s minimal wasm sample. You need a webcam for this.

📷 Open Edge Detection Demo

Quick Start Guide

In addition to normal JS, CSS, HTML and asset files, save your C programs in the same directory. You can take a look at this repo’s demo dir to get an idea.

In your page, include wasup:

<script src="//git.io/wasup"></script>

When needed, intialize the module(s) from files:

wasmModule = await compileWASM('c/filter.c', false, {
  debug: msg => console.log(msg)

This will compile the source file. The second parameter tells wasup that this is a file to be fetched, not a string. The third parameter are callables (functions exported from JS). In order to use callables in your C code, you have to declare them.

In the C program, the first section should be the WASM macro. Let’s take the demo’s source file as an example:

    640 * 480 * 4 * 6,
    void debug(int msg);

Now call functions defined in your C code by using the exports of the wasmModule.

Compile errors are logged to the console like any other exception: