Finagle, is Twitter's open source, high performance RPC Scala library, built on top of Netty, that makes it easy to build multi protocol, asynchronous, scalable distributed applications. Many project have emerged on top of this library like, Finch and Finatra. They are lightweight, powerful web server and REST libraries built on top of Finagle. With micro-services being all the buzz, we will see how Finagle and its ecosystem can be of use, to build and scale applications composed of heterogeneous services