hotpotato (or hptt, for short) is a high performance and throughput oriented HTTP client Java library, with support for HTTP 1.1 pipelining. It was developed mostly towards server-side usage, where speed and low resource usage are the key factors, but it can be used to build client applications as well. Built on top of Netty and designed for high concurrency scenarios where multiple threads can use the same instance of a client without any worries for external or internal synchronization, hotpotato helps you reduce initialization and/or preparation times and resource squandering. Among many small optimizations, connections are reused whenever possible, which results in a severe reduction of total request execution times by cutting connection establishment overhead.
Higgs.IO is a high performance, message oriented network library built for realtime systems. It provides a core extensible framework and libraries built on top of the core. Libraries include a WebSocket server, an HTTP server and client, and Boson, a custom serialization and RMI library.
Corn Httpclient is an HTTP client designed make HTTP requests from Java clients to Web servers as plain requests and form requests. Since authentication requirements are supported, you can make requests to secured Web resources behind the proxies. It supports multiple clients making requests simultaneously with different security credentials.