Netty project - an event-driven asynchronous network application framework

A simple expressive web framework for java. Spark has a kotlin DSL https://github.com/perwendel/spark-kotlin

Asynchronous socket, http(s) (client+server) and websocket library for android. Based on nio, not threads.

Android Asynchronous Networking and Image Loading

MapDB provides concurrent Maps, Sets and Queues backed by disk storage or off-heap-memory. It is a fast and easy to use embedded Java database engine.