Hello Devs, Custom service is very common when it comes to third party integration. Here I will explain using inbound integration to design a custom service and expose the service for integration. Requirement : Need to send list of employees who are on leave today This service will be used by third party Application We will start from creating Response class, 1) Response class 2) A Helper class to hold Response within a list 3) The main Service class to hold logic 4) Simply, Once populating all response values and adding them into list, Return List Response . That is in my case, return ResponseList; 5) Creating service for your service class 5) After service, create service group 6) Assign Service class to Service element 7) Now assign our Service to Service Group (You can drag & drop also) 8) Test your service (On any browser) Structure : Environment URL/API/Services/YourServiceGroupTitle/YourServiceTitle/YourMethod In my case it looks like this, Testing your ...