uWebSockets.js is a high-performance native Node.js addon that wraps the uWebSockets C++ library to provide blazing-fast HTTP/1.1, WebSocket, and QUIC (HTTP/3) server capabilities. It exposes a clean TypeScript/JavaScript API with features such as per-message compression, backpressure management, streaming responses, pub/sub, and SNI support. The architecture centers on a V8 addon compiled for multiple Node.js ABIs (22/24/26) using a custom build script that also builds BoringSSL and lsquic. The JavaScript layer defines a DeclarativeResponse class that encodes response instructions as typed array opcodes for zero-copy native execution. The codebase includes extensive benchmarks with A/B comparison, automated fuzz testing, and a standalone V8 host for testing. While primarily an application library, it incorporates sophisticated data engineering patterns in its benchmarking and performance measurement infrastructure. The repository is actively maintained with recent commits and low open issue count, though it depends on a volatile V8 API and an external submodule.