Announcing support for WASI on Cloudflare Workers

Today, we are announcing experimental support for WASI (the WebAssembly System Interface) on Cloudflare Workers and support within wrangler2 to make it a joy to work with. We continue to be incredibly excited about the entire WebAssembly ecosystem and are eager to adopt the standards as they are developed.

A Quick Primer on WebAssembly

So what is WASI anyway? To understand WASI, and why we’re excited about it, it’s worth a quick recap of WebAssembly, and the ecosystem around it.

WebAssembly promised us a future in which code written in compiled languages could be compiled to a common binary format and run in a secure sandbox, at near native speeds. While WebAssembly was designed with the browser in mind, the model rapidly extended to server-side platforms such as Cloudflare Workers (which has supported WebAssembly since 2017).

WebAssembly was originally designed to run alongside Javascript, and requires developers to interface directly with Javascript in order to access the world outside the sandbox. To put it another way, WebAssembly does not provide any standard interface for I/O tasks such as interacting with files, accessing the network, or reading the system clock. This means if you want to respond to an event from Continue reading