Kwik is a pure Java implementation of the QUIC transport protocol (RFC 9000, RFC 9001, RFC 9369) supporting versions 1 and 2, along with extensions for unreliable datagrams (RFC 9221) and reliable stream reset. It provides both client and server APIs, with a modular architecture consisting of core protocol engine, CLI tool, HTTP/0.9 support, qlog structured logging, and interoperability test harness. The library is designed for embedding in Java applications needing low-latency, multiplexed, encrypted network connections. It includes a custom TLS 1.3 engine (agent15) for handshake management and leverages Java's module system. Extensive unit tests and interop testing against other QUIC implementations ensure protocol compliance. The codebase demonstrates strong engineering practices with clean abstractions (filter chains, builder patterns, null objects), though some features like server connection migration and stream priority remain incomplete.