In today's digital world, knowing about application security is essential. AppSec in a Nutshell is a straightforward guide that explains the key ideas behind securing modern applications, making it a must-read for developers, managers, and security experts. This book provides a clear overview of application security, simplifying complex subjects into easy-to-understand high-level insights. You will learn the basics of AppSec, secure development lifecycle processes, API security, and threat modeling. Designed for those who want to see the overall picture of software security, this book avoids complicated terms and focuses on the key information that everyone involved in software development and security should know.