The best HTTP request made to your server is that one that never reaches it. Do you know the life cycle time of your resources? How to be sure that the user never reaches an expired response without the need to open the connection door with the origin server? What kinds of caches do exist and when do I need to use each one of them? Why can I not be afraid to read the RFCs? This talk will present good practices on the usage of HTTP cache for APIs and web applications, turning your digital products to optimize the usage of machines and save money.