Akka-Http is a akka based http library for building RESTful services in scala. In this series of posts, I will be talking about using akka-http to build REST services. This is the second post in the series. You can access all the posts in this series here.

In this post, we are going to discuss how to use json with akka-http for communicating request and responses

TL;TR You can access complete project on github.

Adding dependency

Akka HTTP uses the akka-http-spray-json library for parsing json request and responses. So add the following dependency to your project.

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


In this example, we are going to create an API which can add/list customers. The following are the steps to add the API.

1. Define customer model

Akka HTTP uses case classes to define the models. So we define a simple customer model which has only name.

case class Customer(name: String)

2. Create Writer/Reader for the model

In spary-json, we have to define the write/reader for a given model in order to be used in the request/response. Most of the time it is very simple as defining the implicit as below.

object ServiceJsonProtoocol extends DefaultJsonProtocol {
    implicit val customerProtocol = jsonFormat1(Customer)

In the above code snippet, we are creating a service protocol which extends the default protocol. Inside this protocol, we can define all the models. In above code, the number ‘1’ in jsonFormat1 signifies there is only one field in case class.

3. Defining the route

Once we have the model and parser implicits, we can define a route which has post for adding a customer and get to get all the added customers.

 val route =
    path("customer") {
      post {
        entity(as[Customer]) {
          customer => complete {
              s"got customer with name ${customer.name}"
        } ~
        get {
          complete {

In above example, an entity is parsed in post request using entity(as). Once we have the customer, we are adding it to a concurrent queue.

In the get method, we are taking all the values in the list and converting to a JSArray.

You can access complete code here.

Now you have a working REST api in akka-http which can handle json data.