spinframework/spin
Spin
Spin is a developer framework for building, running, and distributing serverless applications and microservices compiled to sandboxed WebAssembly components. Components start only when an event arrives, such as an HTTP request or a Redis message, and are discarded afterwards. A single command-line tool covers the workflow: scaffolding from templates, building, running locally, publishing to a registry, and adding commands through plugins.
Each application is described by one declarative manifest that lists its components, triggers, variables, and permissions. Components run in an isolated sandbox and receive only the capabilities they are granted, including checks on outbound network calls against configured rules. Host capabilities such as key-value storage, SQL databases, outbound HTTP, AI inference, and configuration variables are exposed through typed interfaces, with the backing provider chosen through runtime configuration rather than code changes. The runtime is modular, so an embedder can offer a subset of features or add custom triggers for other event sources.
Components can be written in several languages, including Rust, Go, JavaScript, and Python, using language-specific SDKs, and components from different languages can be reused as library dependencies of one another. Data access covers key-value storage, SQLite, MySQL, PostgreSQL, and Redis. Variables and secrets can come from environment variables, static values, Vault, or Azure. Components can also run language model inference using a local model or a remote provider. Templates cover HTTP and Redis components, static file serving, and request redirects.
Applications are packaged as OCI artifacts that container registries can store and deliver. For development, Spin exports OpenTelemetry traces and metrics, includes a Docker Compose observability stack, and provides a diagnostic command that reports misconfigurations with suggested fixes. A directory of example applications is available to start from.
