In this blog we are using Swagger to generate document of Akka-HTTP.
For Swagger you can get more information from Introduction to Swagger .
For Akka you can get more information from Introduction to Akka-Http
You can find complete code here.
build.sbt file of the project contains all dependency.
Get the Json in response by hitting localhost:8080/api-docs/swagger.json
You can get the document by pasting json on http://editor.swagger.io/#/