gin-gonic/gin
Gin is a HTTP web framework written in Go (Golang). It features a Martini-like API with much better performance -- up to 40 times faster. If you need smashing performance, get yourself some Gin.
EricEdens/urllib
A modern URL toolset for Java. Compliant with RFC 3986.
ReactiveX/RxJava
RxJava – Reactive Extensions for the JVM – a library for composing asynchronous and event-based programs using observable sequences for the Java VM.
dragonite-network/dragonite-java
A reliable application level data transport protocol based on UDP, highly optimized for lossy & unstable networks. (Java version)