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0.17.0 Jul 28, 2020

#46 in WebAssembly

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1,159 downloads per month
Used in 35 crates (14 directly)

MIT license

6.5K SLoC

Wasmer is a fast and secure WebAssembly runtime that enables super lightweight containers to run anywhere: from Desktop to the Cloud, Edge and IoT devices.

This document is also available in: πŸ‡¨πŸ‡³ δΈ­ ζ–‡ -Chinese β€’ πŸ‡©πŸ‡ͺ Deutsch-German β€’ πŸ‡ͺπŸ‡Έ EspaΓ±ol-Spanish β€’ πŸ‡«πŸ‡· FranΓ§ais-French β€’ πŸ‡―πŸ‡΅ ζ—₯本 θͺž -Japanese β€’ πŸ‡°πŸ‡· ν•œκ΅­μ–΄ -Korean.


  • Secure by default. No file, network, or environment access, unless explicitly enabled.
  • Supports WASI and Emscripten out of the box.
  • Fast. Run WebAssembly at near-native speeds.
  • Embeddable in multiple programming languages
  • Compliant with latest WebAssembly Proposals (SIMD, Reference Types, Threads, ...)


Wasmer CLI ships as a single executable with no dependencies.

curl https://get.wasmer.io -sSfL | sh
Other installation options (Powershell, Brew, Cargo, ...)

Wasmer can be installed from various package managers. Choose the one that fits best for your environment:

  • Powershell (Windows)

    iwr https://win.wasmer.io -useb | iex
  • Homebrew (macOS, Linux)

    brew install wasmer
  • Scoop (Windows)

    scoop install wasmer
  • Chocolatey (Windows)

    choco install wasmer
  • Cargo binstall

    cargo binstall wasmer-cli
  • Cargo

    Note: All the available features are described in the wasmer-cli crate docs

    cargo install wasmer-cli

Looking for more installation options? See the wasmer-install repository to learn more!


You can start by running QuickJS, a small and embeddable Javascript engine compiled as a WebAssembly module (qjs.wasm):

$ wasmer qjs.wasm
QuickJS - Type "\h" for help
qjs > const i = 1 + 2;
qjs > console.log("hello " + i);
hello 3

Here is what you can do next:

πŸ“¦ Language Integrations

The Wasmer runtime can be used as a library embedded in different languages, so you can use WebAssembly anywhere.

Language Package Documentation
Rust logo Rust wasmer Rust crate Learn
C logo C wasm.h header Learn
C++ logo C++ wasm.hh header Learn
C# logo C# WasmerSharp NuGet package Learn
D logo D wasmer Dub package Learn
Python logo Python wasmer PyPI package Learn
JS logo Javascript @wasmerio NPM packages Learn
Go logo Go wasmer Go package Learn
PHP logo PHP wasm PECL package Learn
Ruby logo Ruby wasmer Ruby Gem Learn
Java logo Java wasmer/wasmer-jni Bintray package Learn
R logo R no published package Learn
Postgres logo Postgres no published package Learn
Swift logo Swift no published package
Zig logo Zig no published package
Dart logo Dart wasm pub package
Crystal logo Crystal no published package Learn
Lisp logo Lisp no published package
Julia logo Julia no published package
VLang logo V no published package
Ocaml logo OCaml wasmer OCaml package

πŸ‘‹  Missing a language?


We appreciate your help! πŸ’œ

We recommend reading the following guide on how to contribute into a complex project successfully: https://mitchellh.com/writing/contributing-to-complex-projects

Check our docs on how to build Wasmer from source or test your changes.


For some issues we offer paid bounties. You'll get paid automatically as soon as your PR solving the issue is merged!

Bounties of wasmerio


Wasmer has an amazing community of developers and contributors. Welcome, please join us! πŸ‘‹


~79K SLoC