Bringing WebAssembly to constrained devices with Rust: Runtimes, tooling, and real-world tradeoffs

In this talk, we will share the insights we gained while building Myrmic, our open-source Rust middleware for distributed systems, with a particular focus on our microcontroller firmware that enables running WebAssembly on resource-constrained targets such as Nordic and ESP devices. Our entire stack is Rust-based—from Embassy firmware and the embedded HAL to the Wasm toolchain and the runtimes themselves. We will outline the requirements that running Wasm in no_std environments imposes on runtimes, particularly in the context of distributed systems with constrained devices. We will then share our experience with Rust-native runtimes such as wasmtime, wasmi, and tinywasm and with embedding WAMR into Rust firmware, focusing on how each runtime aligned with these requirements and the modifications or integration work needed to support our use case. We will also discuss how we structure and compile our Wasm modules, and the trade-offs we make between developer ergonomics, code portability, and the memory footprint of the resulting binaries. The goal of this talk is to provide practical lessons for Rust developers, highlight gaps in today’s embedded-Wasm tooling, and point out opportunities for new open-source contributions.

Links to relevant projets: - wasmtime (https://github.com/bytecodealliance/wasmtime) - wamr (https://github.com/bytecodealliance/wasm-micro-runtime) - wasmi (https://github.com/wasmi-labs/wasmi) - tinywasm (https://github.com/explodingcamera/tinywasm) - A link to Myrmic is not yet available since it will be open-sourced early 2026