In this world where we have moved beyond web pages and build ever-more asynchronous applications, often things that go wrong result in errors we can't see. This session will give a very technical overview of HTTP and how to inspect your application's communications, whether on the web or on a mobile device. Using Curl, Wireshark and Charles, we can quickly and painlessly identify where the problem exists, without spending a lot of time making changes to our application to identify a problem. Whether you're debugging a backend API, an ajax request or an unexpected timeout, these are the tools you will want to have at hand.