<div align="center"> <a href="https://extism.org"> <picture> <source media="(prefers-color-scheme: dark)" srcset=".github/assets/logo-horizontal-darkmode.png"> <img alt="Extism - the WebAssembly framework" width="75%" style="max-width: 600px" src=".github/assets/logo-horizontal.png"> </picture> </a>

</div>

Overview

Extism is a lightweight framework for building with WebAssembly (Wasm). It supports running Wasm code on servers, the edge, CLIs, IoT, browsers and everything in between. Extism is designed to be "universal" in that it supports a common interface, no matter where it runs.

Note: One of the primary use cases for Extism is building extensible software & plugins. You want to be able to execute arbitrary, untrusted code from your users? Extism makes this safe and practical to do.

Additionally, Extism adds some extra utilities on top of standard Wasm runtimes. For example, we support persistent memory/module-scope variables, secure & host-controlled HTTP without WASI, runtime limiters & timers, simpler host function linking, and more. Extism users build:

• plug-in systems
• FaaS platforms
• code generators
• web applications
• & much more...

Supported Targets

We currently provide releases for the following targets:

• aarch64-apple-darwin
• aarch64-unknown-linux-gnu
• aarch64-unknown-linux-musl
• x86_64-apple-darwin
• x86_64-pc-windows-gnu
• x86_64-pc-windows-msvc
• x86_64-unknown-linux-gnu
• x86_64-unknown-linux-musl

For Android we suggest taking a look at the Chicory SDK for a pure Java Extism runtime.

Run WebAssembly In Your App

Pick a SDK to import into your program, and refer to the documentation to get started:

| Type | Language | Source Code | Package | | ----------- | ---------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------- | ----------------------------------------------------------------------- | | Rust SDK | <img alt="Rust SDK" src="https://extism.org/img/sdk-languages/rust.svg" width="50px"/> | https://github.com/extism/extism/tree/main/runtime | Crates.io | | JS SDK | <img alt="JS SDK" src="https://extism.org/img/sdk-languages/js.svg" width="50px"/> | https://github.com/extism/js-sdk <br/>(supports Web, Node, Deno & Bun!) | NPM | | Elixir SDK | <img alt="Elixir SDK" src="https://extism.org/img/sdk-languages/elixir.svg" width="50px"/> | https://github.com/extism/elixir-sdk | Hex | | Go SDK | <img alt="Go SDK" src="https://extism.org/img/sdk-languages/go.svg" width="50px"/> | https://github.com/extism/go-sdk | Go mod | | Haskell SDK | <img alt="Haskell SDK" src="https://extism.org/img/sdk-languages/haskell.svg" width="50px"/> | https://github.com/extism/haskell-sdk | Hackage | | Java SDK | <img alt="Java SDK" src="https://extism.org/img/sdk-languages/java-android.svg" width="50px"/> | https://github.com/extism/java-sdk | Sonatype | | .NET SDK | <img alt=".NET SDK" src="https://extism.org/img/sdk-languages/dotnet.svg" width="50px"/> | https://github.com/extism/dotnet-sdk <br/>(supports C# & F#!) | Nuget | | OCaml SDK | <img alt="OCaml SDK" src="https://extism.org/img/sdk-languages/ocaml.svg" width="50px"/> | https://github.com/extism/ocaml-sdk | opam | | Perl SDK | <img alt="Perl SDK" src="https://extism.org/img/sdk-languages/perl.svg" width="50px"/> | https://github.com/extism/perl-sdk | CPAN | | PHP SDK | <img alt="PHP SDK" src="https://extism.org/img/sdk-languages/php.svg" width="50px"/> | https://github.com/extism/php-sdk | Packagist | | Python SDK | <img alt="Python SDK" src="https://extism.org/img/sdk-languages/python.svg" width="50px"/> | https://github.com/extism/python-sdk | PyPi | | Ruby SDK | <img alt="Ruby SDK" src="https://extism.org/img/sdk-languages/ruby.svg" width="50px"/> | https://github.com/extism/ruby-sdk | RubyGems | | Zig SDK | <img alt="Zig SDK" src="https://extism.org/img/sdk-languages/zig.svg" width="50px"/> | https://github.com/extism/zig-sdk | N/A | | C SDK | <img alt="C SDK" src="https://extism.org/img/sdk-languages/c.svg" width="50px"/> | https://github.com/extism/extism/tree/main/libextism | N/A | | C++ SDK | <img alt="C++ SDK" src="https://extism.org/img/sdk-languages/cpp.svg" width="50px"/> | https://github.com/extism/cpp-sdk | N/A |

Compile WebAssembly to run in Extism Hosts

Extism Hosts (running the SDK) must execute WebAssembly code that has a PDK, or Plug-in Development Kit, library compiled in to the .wasm binary. PDKs make it easy for plug-in / extension code authors to read input from the host and return data back, read provided configuration, set/get variables, make outbound HTTP calls if allowed, and more.

Pick a PDK to import into your Wasm program, and refer to the documentation to get started:

| Type | Language | Source Code | Package | | ------------------ | ---------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------- | --------------------------------------------------------- | | Rust PDK | <img alt="Rust PDK" src="https://extism.org/img/sdk-languages/rust.svg" width="50px"/> | https://github.com/extism/rust-pdk | Crates.io | | JS PDK | <img alt="JS PDK" src="https://extism.org/img/sdk-languages/js.svg" width="50px"/> | https://github.com/extism/js-pdk | N/A | | Python PDK | <img alt="Python PDK" src="https://extism.org/img/sdk-languages/python.svg" width="50px"/> | https://github.com/extism/python-pdk | N/A | | Go PDK | <img alt="Go PDK" src="https://extism.org/img/sdk-languages/go.svg" width="50px"/> | https://github.com/extism/go-pdk | Go mod | | Haskell PDK | <img alt="Haskell PDK" src="https://extism.org/img/sdk-languages/haskell.svg" width="50px"/> | https://github.com/extism/haskell-pdk | Hackage | | AssemblyScript PDK | <img alt="AssemblyScript PDK" src="https://extism.org/img/sdk-languages/assemblyscript.svg" width="50px"/> | https://github.com/extism/assemblyscript-pdk | NPM | | .NET PDK | <img alt=".NET PDK" src="https://extism.org/img/sdk-languages/dotnet.svg" width="50px"/> | https://github.com/extism/dotnet-pdk <br/>(supports C# & F#!) | Nuget | | C PDK | <img alt="C PDK" src="https://extism.org/img/sdk-languages/c.svg" width="50px"/> | https://github.com/extism/c-pdk | N/A | | C++ PDK | <img alt="C++ PDK" src="https://extism.org/img/sdk-languages/cpp.svg" width="50px"/> | https://github.com/extism/cpp-pdk | N/A | | Zig PDK