This book assumes a familiarity with both web application engineering and the basics of web application security. Any experience with the frontend technologies that will provide the interface and context for many of your discoveries is an asset, including a basic understanding of HTML/CSS/JS, and the DOM; the client-server relationship, session management (cookies, TTL, and so on); and the browser environment. In addition, a general acquaintance with the RESTful API architecture, popular application frameworks and languages (Django/Python, RoR/Ruby, and so on), common application security techniques, and common vulnerabilities, will all be handy. You might be a full-time security researcher, a moonlighting web application engineer, or even just a programming enthusiast with a light background and a historical interest in security – you'll all find something useful within these pages. If you're just beginning, that's OK too – working through the step-by-step walk-through in later chapters will help you develop as a security researcher; you just might need to fill in the gaps with outside context.
In addition to these topics, it's assumed you'll also have experience using the command line. While many great graphic tools exist for conducting and visualizing penetration testing engagements, and we'll use many of them, the CLI is an invaluable tool for everything from package management, to real-time pentesting execution, to automation. And while many of the tools used will have a compatible Windows counterpart, the actual engagements will be conducted (for the most part) on a 2015-generation MacBook Pro loaded with High Sierra (10.13.2), if you are working on a Windows PC, you can still participate by using a virtual machine or emulation software.