Abstract: Server less is the current buzzword in IT applications. There has been increased adoption to server less technologies provided by major cloud providers. Azure Functions is an offering from Microsoft in Azure in the area of Function as a service (Faas). Azure Functions provide two billing modes mainly consumption model or app service model. This talk will go through the scenarios where we will explore the wrong ways of building applications using Azure Functions and how one can avoid these pitfalls and prevent them from heavy billing based on usage. The talk will also go over the different ways of testing Azure Functions and how one can use application insights to avoid the pitfalls. A working session will be conducted with samples and attendees will get all information on developing applications using Azure Functions in an effective way.