Why Should You Care About WebAssembly

WebAssembly, fundamentally, is a binary instruction set. It’s similar to assembly languages you may have heard of, like x86 or ARM, but with some new characteristics and security guarantees. You write code in a programming language like C or Rust and that code can be compiled into a WebAssembly artifact. As Wasm was initially created for the web, the major appeal was that you could run high performance applications on the web at near-native speeds, though WebAssembly today is experiencing wide adoption outside of the browser as well.

One thing that sets Wasm apart from other compiler targets is its portability. WebAssembly code can be run on any platform so long as there is a runtime for it, regardless of the underlying architecture. This means that developers can write their code once and expect it to run everywhere—whether that’s on Windows, macOS, Linux, mobile operating systems, in the browser, or even on a lightbulb.

Security is absolutely paramount, especially in the digital world we live in today. As such, WebAssembly was created with security as a core design goal. Let’s take a moment to think about what web browsers do. When you visit a web page, your browser downloads unknown, untrusted code and executes it—completely terrifying when you really think about it. It’s the job of your browser to protect you and your device from malicious code, and it’s that exact mindset that’s built into WebAssembly with:

1. Sandboxing: This isolates WebAssembly code from the host environment, preventing it from accessing unauthorized data or determining any information about where the code is running.
2. Deny-by-default access: WebAssembly has a very strict deny-by-default security policy, meaning it’s not allowed to access system resources without explicit permission. This even goes as far as simple resources like the system time—not at all available unless specifically shared with the Wasm code.
3. Memory boundaries: Each running WebAssembly instance gets its own chunk of memory that it cannot see beyond, completely isolated from other WebAssembly instances and the host memory.

WebAssembly was designed to be fast. Compared to JavaScript, Wasm code can be decoded and start executing before JavaScript code can even be parsed. It enables new experiences in browsers, but also offers near-native performance outside of the browser with its portability and security guarantees.

It’s not at all about replacing JavaScript. The two are complementary technologies and were designed to fit together rather than compete. JavaScript is still necessary for the dynamic and interactive parts of web apps, while Wasm is being used more for computationally expensive tasks.

Since WebAssembly code executes within a runtime, it’s easy to drop it into an existing application—whether it’s a web application or an application running at the edge or on the server. This allows you to extend your application with code written in nearly any language or even untrusted code from third parties. This makes WebAssembly well-suited for plugin systems, as you can safely run code within your application provided by community members or customers. WebAssembly’s great security model makes this all possible.

WebAssembly has made a huge splash in serverless computing. Compared to containers, Wasm modules are tiny—most modules produced are on the order of kilobytes or single-digit megabytes, whereas containers can easily be hundreds of megabytes or several gigabytes. Besides just storage size, Wasm also solves the famous “cold start” problem—Wasm code can start executing in microseconds, and thus doesn’t need to leave code running to be able to respond to requests quickly. You could spin up a Wasm instance when a request is received with very minor effects on latency. This means WebAssembly-based systems can scale all the way down to zero when there’s no traffic—a blessing to both Mother Nature and your bank account.

In my opinion, the real game-changer is the WebAssembly Component Model. It will fundamentally change the way developers construct and compose software through its:

1. Cross-ecosystem access: Want the cryptography libraries from Go, a JSON serializer from Rust, and number crunching utilities from Python? No problem. With the Component Model, you can select software from nearly any language ecosystem and compose them together as though they were native libraries all written in the same language.
2. Development flexibility: Different teams within an organization can choose the best tool for the job. They can select programming languages and software stacks that cater to their expertise and project requirements, with the confidence that their team’s deliverables will link seamlessly into the full application.

Simply put, developers can build software components in any language that can produce WebAssembly code and then easily compose them into a single application.

WebAssembly is a technology that merits your attention. Whether you’re a developer looking to add new capabilities to your application, or a business focused on building scalable and cost-efficient solutions, Wasm might be right for you. As it continues to mature and gain support, WebAssembly stands poised to redefine the way we think about and interact with software development. Keep an eye on WebAssembly because it’s not just the future—it’s already here, reshaping software as we know it.

Want to learn more about WebAssembly? Check out F5’s WebAssembly Unleashed podcast on YouTube, Spotify, or Apple Podcast.