Netty
/ˈnɛt.i/ · Noun · Development
Definitions
An asynchronous, event-driven network application framework for the JVM that provides a high-performance, non-blocking I/O pipeline for building protocol servers and clients — used internally by Elasticsearch, Cassandra, gRPC-Java, and Play Framework.
In plain English: A popular Java toolkit for building fast network servers that can handle a huge number of connections without slowing down.
Example: "We built the WebSocket gateway on Netty because it handles 500K concurrent connections on a single box without spawning a thread per socket."