Most APIs are built on assumptions . Assumption that users are trusted. Assumption that internal services are safe. Assumption that tokens won't be abused. That's exactly why they fail. Zero Trust APIs is a practical guide for developers who want to design systems that don't rely on trust at all . This book shows you how to build APIs where: Every request is verified Every service is treated as potentially hostile Every token is validated and controlled Every failure is contained You'll learn how to move from "it works" to "it survives attacks." What You'll Learn How Zero Trust principles apply to API design Authentication vs Authorization (and why most get it wrong) Secure token handling (JWT, API keys, rotation strategies) Protecting internal APIs from lateral movement attacks Rate limiting and abuse prevention techniques Designing service-to-service authentication securely Building resilient systems with least privilege access Logging, monitoring, and detecting suspicious behavior Why This Book is Different This is not theory. This is not compliance talk. This is a developer-first, production-focused playbook filled with: Real-world scenarios Simple architecture patterns Practical implementation strategies Who This Book is For Backend developers building APIs Engineers working with microservices SaaS founders handling sensitive data DevOps teams securing infrastructure What You'll Achieve By the end of this book, you'll be able to: Design APIs that assume breach by default Eliminate common security blind spots Build systems that scale securely Sleep better knowing your backend won't collapse under attack If your API is exposed to the internet, this is not optional.