Web applications deserve to outlive the currently fashionable framework. Your application's core use cases deserve to be decoupled from their surrounding infrastructure. And all of your domain-specific code needs to be testable; it has to be tested after all. This book helps you get your web applications back in shape. It contains many techniques for decoupling from infrastructure (like the framework, the database, or remote web services). In Part 1 we unlock a collection of design patterns which help you establish a clean separation between core and infrastructure code. Part 2 shows how these design patterns resonate at a higher level with architectural concepts like layers, ports and adapters (a.k.a. Hexagonal architecture). The book finishes with a discussion of testing strategies and design trade-offs. What you'll learn - Separating mixed code into core and infrastructure code by refactoring into patterns - Dividing your code into layers, and making a clear distinction between an application's ports and adapters - Testing decoupled applications Each chapter comes with exercises to test your understanding. This is a book for experienced web developers. Code samples are written in PHP and are easy to follow by developers who write code in other OOP dialects, like C#, Java, etc.