Alberto Schiabel Senior Software Engineer and Former Startup Co-Founder Traditionally, Node.js has delegated the task of writing complex CPU-intensive logic to C++, but the increasing adoption of Rust and WebAssembly has led to a paradigm shift. In fact, Rust code can be compiled to WASM and be imported in a JavaScript (or even TypeScript) source file - for instance, Seed and Prisma follow this approach -, but that doesn’t come without limitations and gotchas, even for relatively small projects that abide to standard Rust patterns. From silenced warnings and obfuscated panic errors to structs that cannot be serialized and typed automatically, the path of porting Rust code to a JS app in production is a steep one, even when we don’t consider the I/O limitations that WASI should address. In this presentation, we will look at a language parser written in Rust, compiled with wasm-bindgen and interpreted by Node.js, observing some limitations for production use cases and discussing alternatives. There’s no free lunch: WebAssembly - albeit useful - comes with its own set of challenges, and I trust this talk will help you navigate potential issues before they impact your deadlines.