WebAssembly is a powerful new technology for developing and running applications on the web, in browsers, and elsewhere. Learning how to harness this technology is essential to understanding the future of web development. By using WebAssembly to run code from a variety of languages in the browser without plugins or external technologies, the web is moving beyond the HTML, CSS, and JavaScript paradigm. With this practical, hands-on book, web developers will learn how to interact with and create WebAssembly modules. Author Kassian Wren shows you which languages and toolchains are available for WebAssembly, how to write WebAssembly modules in Rust and AssemblyScript, and how to optimize WebAssembly modules for more performant websites. You'll quickly understand how this technology will impact not just the web, but also the way we think about developing applications across a variety of platforms. With this book, you'll learn: How WebAssembly works and when it should be used Some languages and toolchains that are available for WebAssembly How to write and use a WebAssembly module, in Rust and AssemblyScript How to write WebAssembly modules in Rust and use WebAssembly with web workers How to optimize WebAssembly modules for better site performance