Hyper4J (short for "HyperTextTransferProtocol for Java") is an embeddable NIO HTTP server implemented in Java with no external dependencies.
It currently supports HTTP 1.0/1.1 and TLS. It is intended as a low-level HTTP server implementation and does not provide a Servlet context (though it could be used to implement one) or any built-in request handling. It was originally created for use in an Android application and as such is compatible with a range of Android platforms as well as other Java environments.