Wasm3 Save

🚀 The fastest WebAssembly interpreter, and the most universal runtime

Project README



WAPM GitHub issues Tests status Fuzzing Status GitHub license

The fastest WebAssembly interpreter, and the most universal runtime.
Based on CoreMark 1.0 and independent benchmarks. Your mileage may vary.

Twitter Discord Telegram

Getting Started

Here's a small getting started guide. Click here to start:



Please follow the installation instructions.

Wasm3 can also be used as a library for:

Python3 Rust C/C++ GoLang Zig Perl
Swift .Net Nim Arduino, PlatformIO, ParticleQuickJS


wasm3 passes the WebAssembly spec testsuite and is able to run many WASI apps.

Minimum useful system requirements: ~64Kb for code and ~10Kb RAM

wasm3 runs on a wide range of architectures (x86, x86_64, ARM, RISC-V, PowerPC, MIPS, Xtensa, ARC32, ...) and platforms:

  • Linux, Windows, OS X, FreeBSD, Android, iOS
  • OpenWrt, Yocto, Buildroot (routers, modems, etc.)
  • Raspberry Pi, Orange Pi and other SBCs
  • MCUs: Arduino, ESP8266, ESP32, Particle, ... see full list
  • Browsers. Yes, using WebAssembly itself!
  • wasm3 can execute wasm3 (self-hosting)


Webassembly Core Proposals Extra
☑ Import/Export of Mutable Globals ☑ Structured execution tracing
☑ Non-trapping float-to-int conversions ☑ Big-Endian systems support
☑ Sign-extension operators ☑ Wasm and WASI self-hosting
☑ Multi-value ☑ Gas metering
☑ Bulk memory operations (partial support) ☑ Linear memory limit (< 64KiB)
☐ Multiple memories
☐ Reference types
☐ Tail call optimization
☐ Fixed-width SIMD
☐ Exception handling


Why use a "slow interpreter" versus a "fast JIT"?

In many situations, speed is not the main concern. Runtime executable size, memory usage, startup latency can be improved with the interpreter approach. Portability and security are much easier to achieve and maintain. Additionally, development impedance is much lower. A simple library like Wasm3 is easy to compile and integrate into an existing project. (Wasm3 builds in a just few seconds). Finally, on some platforms (i.e. iOS and WebAssembly itself) you can't generate executable code pages in runtime, so JIT is unavailable.

Why would you want to run WASM on embedded devices?

Wasm3 started as a research project and remains so by many means. Evaluating the engine in different environments is part of the research. Given that we have Lua, JS, Python, Lisp, ... running on MCUs, WebAssembly is actually a promising alternative. It provides toolchain decoupling as well as a completely sandboxed, well-defined, predictable environment. Among practical use cases we can list edge computing, scripting, plugin systems, running IoT rules, smart contracts, etc.

Used by


Further Resources

Installation instructions
Build and Development instructions
Supported Hardware
Testing & Fuzzing
Interpreter Architecture
Awesome WebAssembly Tools


This project is released under The MIT License (MIT)

Open Source Agenda is not affiliated with "Wasm3" Project. README Source: wasm3/wasm3

Open Source Agenda Badge

Open Source Agenda Rating