extism/extism
Extism
Extism is a cross-language WebAssembly plugin framework that lets applications written in any programming language load and execute plugins written in any other language. It provides a universal plugin system where host applications use idiomatic SDKs to load WebAssembly modules, call exported functions, and pass data back and forth, while plugin authors use development kits that handle memory management and host interaction so they can focus on business logic.
The framework distinguishes itself through its comprehensive approach to cross-language integration, offering schema-driven binding generation that creates type-safe interfaces between host and plugin code from a shared definition. It includes a plugin development kit for each supported language that automatically handles input parsing, output serialization, and host function calls, along with a manifest-based loading system that sets runtime constraints and allowed capabilities before module instantiation. A command-line interface provides tools for invoking plugin functions, scaffolding new plugin projects, and managing the runtime installation.
Extism manages the full lifecycle of plugin systems, from defining plugin interfaces and loading WebAssembly modules to managing persistent module state and testing plugins within a host environment. It handles host-plugin memory management through a shared memory bridge, supports custom host function registration for providing application-specific capabilities to plugins, and enables rapid deployment of plugin systems without building infrastructure from scratch. The framework also provides controlled HTTP request capabilities and configuration reading from the host.
The project includes a runtime manager that installs and checks the version of the shared library required by all host SDKs, and supports compiling plugins from supported languages into WebAssembly binaries for any Extism host environment.
Features
- Cross-Language Host SDKs - Provides idiomatic host SDKs for multiple languages to integrate WebAssembly plugins into applications.
- WebAssembly Function Callings - Calls named functions inside loaded WebAssembly modules and receives return values through the host SDK.
- Plugin Development Kit Stubs - Generates boilerplate code in each plugin language that handles input parsing, output serialization, and host function calls.
- Type-Safe Binding Generators - Generates type-safe bindings from a shared schema to ensure consistent interfaces across host and plugin languages.
