Rust and WebAssembly: Bridging the Gap

Rust and WebAssembly: Bridging the Gap

The advent of Rust and WebAssembly (Wasm) has led web programming into a new era of performance and reliability. They both have emerged as two innovative technologies giving a revitalizing design to the entire web ecosystem. This guide intends to provide you with the insights needed to appreciate the synergies between Rust and WebAssembly and explain how to leverage the functionalities of both.

What is Rust? Why is it becoming a popular choice among developers?

Rust is a system-level programming language designed with an emphasis on memory safety and zero runtime errors. This focus is why Rust has been voted as the "most loved language" by developers in StackOverflow's annual developer survey for four consecutive years. Rust offers memory safety without garbage collection and gives developers the ability to write code that executes close to the processor, enhancing the potential for better performance.

What is WebAssembly? How does it revolutionize web application development?

WebAssembly (Wasm) is a binary instruction format running in modern web browsers. It provides a stack-based virtual machine with a compact binary format that allows high-speed parsing and efficient execution. The introduction of Wasm can be a game-changer in web development as it allows you to run languages other than JavaScript at near-native speed in the browser.

How does Rust work with WebAssembly?

Rust and WebAssembly work together in a seamless and proficient fashion. Rust compiles to LLVM "bitcode," which the WebAssembly backend can convert into Wasm bytecode. Then, this bytecode can run seamlessly within a web environment. Bridging Rust and WebAssembly brings performance and safety to the front-end world.

Why integrate Rust with WebAssembly?

There are several reasons to integrate Rust with WebAssembly:

  1. Performance: WebAssembly code executes at near-native speed by taking advantage of common hardware capabilities. Since Rust is capable of fine-grained control over system resources and has a small runtime, it is ideal for creating performant WebAssembly modules.

  2. Safety: Rust guarantees memory safety without needing a garbage collector, making it efficient and reliable. When Rust code is compiled to WebAssembly, you get this same safety assurance on the web.

  3. Interoperability: With Rust and WebAssembly, you're not limited to JavaScript. You can use the benefits of Rust libraries and modules in your web applications.

How to integrate Rust and WebAssembly in a actionable way?

Let’s go through the steps involved in setting up a minimal integration of Rust and WebAssembly:

  1. Install Rust and Wasm-pack: First, you need to set up the Rust development environment. After installing Rust, install wasm-pack, a tool for assembling and packaging Rust crates that target WebAssembly.

    curl -sSf | sh
    cargo install wasm-pack
  2. Create a new Rust Library: Create a new library using the following command.

    cargo new --lib mylib
  3. Write some Rust Code: Write Rust code in the src/ file in your new lib.

    pub fn add(a: i32, b: i32) -> i32 {
       a + b
  4. Add WebAssembly as a target in Cargo.toml file: Modify the Cargo.toml file in your project to add wasm32-unknown-unknown as your target.

    crate-type = ["cdylib"]
  5. Compile the Rust code to Wasm: You’ll use Wasm-pack to do the compilation.

    wasm-pack build --target web
  6. Integrate WebAssembly module with JavaScript: Now you can import your WebAssembly code in your JavaScript file and then use it as you'd use any other JavaScript module.


The landscape of web programming is rapidly evolving, and Rust and WebAssembly are at its forefront. By marrying the speed of Rust with the efficiency and portability of WebAssembly, developers can now create incredibly performant and reliable web applications. With the techniques outlined in this guide, you are now equipped to start exploring the world of Rust and WebAssembly.


Q: Can I use Rust without WebAssembly? A: Yes, Rust can be used independently of WebAssembly. It's a general-purpose language that runs directly on hardware or anywhere you would run C/C++.

Q: Is learning Rust and WebAssembly tough for a beginner? A: There is a learning curve to both, particularly Rust. But once you get over the initial hurdle, you will appreciate the capabilities they offer.

Q: What is an instance where the Rust and WebAssembly combination is particularly useful? A: Performing CPU-intensive tasks such as image or video editing, 3D rendering, or scientific simulation on the client side can leverage the Rust and WebAssembly combination for better performance and efficiency.