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# From Bytes to Execution: Writing a WebAssembly Runtime in Rust


- **Date:** Thursday, Jul 9, 2026
- **Time:** 14:10–14:40 (30 min)
- **Room:** Stage 10 - powered by TikTok
- **Event:** World Congress 2026 Europe

## Recording

[Watch recording](https://www.wearedevelopers.com/videos/100094-from-bytes-to-execution-writing-a-webassembly-runtime-in-rust)

## Description

WebAssembly runtimes power everything from serverless platforms to container sandboxes — but their internals often feel opaque. In this talk, I demystify those internals by presenting Whisk, a minimal WebAssembly runtime I built entirely in Rust.

Rather than focusing on a production-grade engine, Whisk intentionally strips the runtime down to its essential components: module parsing, validation, memory handling, and instruction execution. Walking through these pieces makes the architecture of a WASM runtime clear and approachable, while also showing how Rust’s enums, traits, and safety guarantees naturally support VM design.

We’ll explore how an interpreter is built step-by-step, what trade-offs arise in a minimal design, and how Whisk differs from larger runtimes like Wasmtime or Wasmer. I’ll also demo Whisk running real WebAssembly modules (non-WASI), illustrating where the boundaries of a tiny runtime lie.

Attendees will learn:
- How a WebAssembly runtime works from the inside out
- How to design a small interpreter in Rust
- Why Rust is well-suited for building VMs and sandboxes
- The trade-offs between minimal and production-grade runtimes
- How lightweight engines fit into today’s WASM and cloud-native ecosystem

This talk offers a practical and accessible deep dive into WebAssembly internals — with Rust as the guide.

## Speaker

### [Gaurav Gahlot](https://www.wearedevelopers.com/@gaurav-gahlot)

Staff Software Engineer at IONOS Cloud


## Related talks at this congress

- [Native Speed, Java Comfort: Calling Rust from the JVM with Project Panama](https://www.wearedevelopers.com/events/world-congress-2026-europe/sessions/1379-native-speed-java) — Gonzalo Ortiz Jaureguizar
- [Type Systems You Might Not Know (But Will Love)](https://www.wearedevelopers.com/events/world-congress-2026-europe/sessions/1042-type-systems-you) — Veit Heller
- [Simple, Clean, Intuitive, and Qrisp: Quantum Linear Algebra for Developers](https://www.wearedevelopers.com/events/world-congress-2026-europe/sessions/1017-simple-clean) — Matic Petrič
- [Rust on Robots: Hands-on Embedded Rust on STM32](https://www.wearedevelopers.com/events/world-congress-2026-europe/sessions/942-rust-on-robots-hands) — Robert Jeutter