A lot of people have being using Rails to develop both their internal or external API, but building a high quality API can be hard, and performance is a key point to achieve it. I'll share my stories with APIs, and tell you how Active Model Serializer, component of Rails-API, helped me. AMS have being used across thousands of applications bringing convention over configuration to JSON generation. This talk will give you a sneak peek of a new version of AMS that we have being working on, it's new cache conventions, and how it's being considered to be shipped by default in new Rails 5.