Akka HTTP is a akka based http library for building RESTful services in Scala. It’s is based on new Akka reactive streams library.

In this series of posts, I will be talking about how to build REST services using akka-http library.

This is the first post in the series, where I will be talking about setting up the project and running a hello world program.

TL;TR You can access complete code on github.

Adding dependency

To start using akka-http, you should add the following dependency to project. I am using sbt for build management. You can also use other build tools like maven.

"com.typesafe.akka" %% "akka-http-experimental" % "1.0"

Though the artifact name says it’s experimental many companies are using it in the production.

You can access complete build.sbt here

HelloWorld application

The following are the steps to be followed to create a hello world application.

1. Create Actor System

Akka HTTP uses akka actors for handling concurrent requests. So in the first line we have to create akka actor system.

implicit val actorSystem = ActorSystem("system")

2. Create ActorFlowMaterilizer

Akka HTTP uses akka reactive streams for stream processing on TPC. So in a reactive system,we need to specify flow materializer which specifies the how requests/repose flow get processed. In akka-http, actors will be used for handling request and response flows. So we use ActorMaterializer here.

implicit val actorMaterializer = ActorMaterializer()

Please make sure both of the variables are implicits. Otherwise you may get strange cryptic compilation errors.

3. Defining the route

Route specifies the URI endpoints REST server exposing. It is combination of multiple paths.

A simple path has the following three parts

  • Directive/URI
  • HTTP Method
  • Response
val route =
  pathSingleSlash {
    get {
      complete {
        "Hello world"

In above example, we are creating a route with following properties

  • / is the directive
  • get is HTTP Method
  • Returns “hello world” as the response

4. Bind

Once we have all pieces in place, we need to create a server and bind to this route, address and port.


This creates and runs a simple http server at http://localhost:8080.

You can access complete code for this server here.

Now we have a working simple http server using akka-http library.