Designing scalable, user-focused, and robust APIs that last isn’t just a technical challenge but a design imperative. Written by API leaders with over 30 years of combined experience in API strategy, governance, and community, this book is your comprehensive guide to API design, focusing on domain-driven, consumer-centric APIs that meet real user needs while remaining flexible and maintainable over time. It covers modern REST API design, tools like OpenAPI and JSON Schema, and the importance of a product-based approach. The chapters help you explore best practices, potential pitfalls, and anti-patterns, extending beyond the design phase. Starting with the “why” behind building an API, its intended users, and value, this book walks you through the API lifecycle, the role of contracts, and applying domain-driven design. You’ll develop a solid foundation in REST API design as you discover different styles, constraints, and more. Beyond design, the book covers testing techniques, API evolution, maintenance, and deprecation. By the end, you’ll not only know how to design great APIs but understand how to treat them as products, manage their lifecycle, and deliver real value by keeping your APIs relevant and reliable long after release. *Email sign-up and proof of purchase required