Web API with ASP.NET Core 9 is a comprehensive, hands-on guide to building modern, scalable, and secure Web APIs using ASP.NET Core. This book is designed for developers who want to learn how real-world APIs are built, structured, and deployed. It takes a practical approach, guiding readers step by step from project setup to deploying a production-ready API.

ASP.NET Core Web API is the backbone of modern backend development, powering mobile applications, web applications, microservices, and cloud-based systems. This book helps you understand how Web APIs work behind the scenes and how to design clean, maintainable APIs using industry-standard practices. By focusing on clarity and real implementation, the book enables readers to confidently build APIs from scratch using modern .NET technologies.

Why You Should Learn ASP.NET Core Web API

ASP.NET Core Web API is one of the most widely used frameworks for building high-performance, cross-platform backend services. Learning Web API development is essential for backend developers, full-stack developers, and cloud engineers working with modern applications.

Understanding ASP.NET Core Web APIs allows you to build secure RESTful services, integrate databases, implement authentication and authorization, and expose data to web and mobile clients efficiently. With the rise of microservices and cloud-native applications, Web API skills are critical for building scalable and maintainable systems.

What Makes This Book Different?

This book focuses on end-to-end, real-world implementation rather than isolated concepts. It is designed to show how all the pieces of a production-grade Web API fit together. The book emphasizes:

• Clean architecture using repository and service layers

• Asynchronous CRUD operations and best practices

• DTO-based API design with AutoMapper

• Centralized validation and error handling

• JWT authentication and role-based authorization

• Logging, caching, testing, and performance optimization

• Real-time communication and cloud deployment

Readers do not just learn individual features—they learn how to build a complete, working API that follows professional development standards.

Who Should Read This Book?

This book is ideal for:

• Developers new to ASP.NET Core Web API

• Backend and full-stack developers

• Software engineers preparing for real-world projects

• Students learning modern .NET backend development

• Developers migrating to modern ASP.NET Core practices

Basic knowledge of C# is helpful, but the book explains concepts clearly and progressively.

Chapter Overview

Step 1: Project Setup

This chapter lays the foundation for building an ASP.NET Core Web API. It introduces the project architecture, folder structure, and essential tools required to get started. Readers learn how to set up a clean project using the latest .NET LTS version, configure Entity Framework Core, connect to SQL Server, and prepare the application for scalable development.

Step 2: Async CRUD API using Repository + Service Layers in .NET Core Web API

This chapter focuses on implementing asynchronous CRUD operations using the Repository and Service Layer patterns. Readers learn how to separate business logic from data access, build clean and testable code, and expose RESTful endpoints using controllers that interact only with the service layer.

Step 3: AutoMapper + DTO Integration in ASP.NET Core Web API

This chapter explains how to use Data Transfer Objects (DTOs) to control data flow between the API and clients. Readers learn to integrate AutoMapper for efficient object mapping, helping to decouple domain models from API contracts and improve security, maintainability, and code clarity.

Step 4: FluentValidation – Add Model Validation

This chapter introduces server-side validation using FluentValidation. It demonstrates how to validate incoming API requests with clean, reusable validation rules while keeping validation logic separate from domain models, resulting in more maintainable and readable code.

Step 5: Global Error Handling Middleware (Catch All Exceptions Globally)

This chapter covers centralized exception handling using custom middleware. Readers learn how to catch unhandled exceptions globally, log errors, and return standardized JSON error responses, ensuring consistent error handling across the entire application.

Step 6: JWT Authentication & Authorization

This chapter explains how to secure the Web API using JWT-based authentication and authorization. Readers learn how to implement user registration and login, hash passwords securely, generate JWT tokens, and protect API endpoints using authorization attributes.

Step 7: Pagination, Filtering, Sorting

This chapter focuses on improving API performance and usability by implementing pagination, filtering, and sorting. Readers learn how to process query parameters efficiently, limit data loads, and provide flexible data retrieval options to API consumers.

Step 8: Role-based Authorization (Admin/User)

This chapter introduces role-based authorization using JWT claims. Readers learn how to assign roles to users, embed roles within JWT tokens, and restrict access to specific endpoints based on user roles, enabling fine-grained access control.

Step 9: Logging with Serilog

This chapter covers structured logging using Serilog. Readers learn how to configure logging for console and file outputs, capture application events and exceptions, and improve observability and diagnostics in real-world ASP.NET Core applications.

Step 10: Soft Deletes & Audit Trail in ASP.NET Core Web API

This chapter explains how to implement soft delete functionality and maintain an audit trail. Readers learn how to prevent permanent data loss, track creation and modification details, and use global query filters to manage deleted records transparently.

Step 11: Unit Testing in ASP.NET Core Web API using xUnit + Moq

This chapter introduces unit testing using xUnit and Moq. Readers learn how to test service-layer logic in isolation, mock dependencies, validate business logic, and ensure code reliability while supporting refactoring and CI/CD workflows.

Step 12: File/Image Upload in Web API (with Local Storage or Azure Blob)

This chapter demonstrates how to implement file and image upload functionality in a Web API. Readers learn how to handle multipart form data, store uploaded files securely, save file paths in the database, and expose uploaded content via static file hosting.

Step 13: Deploy ASP.NET Core Web API to Azure App Service

This chapter guides readers through deploying an ASP.NET Core Web API to Azure App Service. It covers deployment using Visual Studio and Azure CLI, configuring cloud resources, and testing the API in a live production environment.

Step 14: Caching in ASP.NET Core Web API (In-Memory + Redis)

This chapter focuses on improving API performance through caching. Readers learn how to implement in-memory caching and Redis-based distributed caching to reduce database calls, improve response times, and support scalable application architectures.

Step 15: SignalR for Real-time Notifications

This chapter introduces real-time communication using SignalR. Readers learn how to broadcast live updates from the server to connected clients, enabling features such as notifications, live data updates, and real-time application interactions.