Spin
Fermyon's serverless framework built on WebAssembly + WASI. Functions in Rust/Go/JS/Python/TinyGo compile to Wasm, run as lightweight isolated sandboxes.
Open-sourced 2022. Fermyon (founded by Matt Butcher and others) builds Spin + Fermyon Cloud. CNCF Sandbox 2023. Pitch: faster cold start (~1ms) than containers or AWS Lambda, secure isolation, multi-language. Competitors: Cloudflare Workers (own Wasm stack), Fastly Compute (also Wasm), AWS Lambda (containers).