ASP.NET Core Complete Tutorial (ShopNest)
Lesson 38 of 75 51% of course

Swagger / OpenAPI Documentation in ASP.NET Core

1 · 5 min · 5/24/2026

Learn Swagger / OpenAPI Documentation in ASP.NET Core in our free ASP.NET Core Complete Tutorial (ShopNest) series. Step-by-step explanations, examples, and interview tips on Toolliyo Academy.

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Swagger / OpenAPI Documentation in ASP.NET Core — ShopNest
Article 38 of 75 · Module 5: Web API · ShopNest Developer-Facing API
Target keyword: swagger asp.net core · Read time: ~26 min · .NET: 8 / 9 · Project: ShopNest Developer-Facing API

Introduction

Swagger UI (OpenAPI) lets ShopNest partners explore and test the Product API without reading source code — essential for developer-facing APIs and campus project demos.

After this article you will

  • Configure Swashbuckle in ASP.NET Core
  • Add XML doc comments to controllers
  • Document JWT bearer security in Swagger
  • Support API versioning in Swagger UI
  • Know Scalar as modern UI alternative

Prerequisites

Concept deep-dive

builder.Services.AddSwaggerGen(options =>
{
    options.SwaggerDoc("v1", new OpenApiInfo { Title = "ShopNest API", Version = "v1" });
    var xml = Path.Combine(AppContext.BaseDirectory, "ShopNest.Api.xml");
    options.IncludeXmlComments(xml);
    options.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
    {
        Name = "Authorization",
        Type = SecuritySchemeType.Http,
        Scheme = "bearer",
        BearerFormat = "JWT"
    });
    options.AddSecurityRequirement(new OpenApiSecurityRequirement { ... });
});

if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "ShopNest v1"));
}

Enable XML docs in .csproj: <GenerateDocumentationFile>true</GenerateDocumentationFile>

/// summary comments appear in Swagger for each endpoint. Scalar — drop-in modern alternative to Swagger UI.

Hands-on — ShopNest Developer-Facing API

  1. Add Swashbuckle; browse /swagger in Development.
  2. XML comments on ProductsController actions.
  3. Authorize button — paste JWT from login endpoint.
  4. Generate C# client with NSwag or OpenAPI Generator (optional).

Common errors & best practices

  • Swagger exposed in Production without auth — disable or protect with policy.
  • Missing XML file path — build fails silently without comments.

Interview questions

Q: OpenAPI vs Swagger?
A: OpenAPI is the spec; Swagger is tooling (UI + codegen) implementing it.

Q: Swashbuckle vs NSwag?
A: Both popular; Swashbuckle most common in ASP.NET Core tutorials.

Summary

  • Swagger documents REST contracts for humans and codegen
  • JWT security definition enables Try-it-out with auth
  • XML comments improve partner developer experience
  • Disable or lock down Swagger in production

Previous: API Versioning
Next: Input Validation in Web APIs

FAQ

Swagger in .NET 9?

Built-in OpenAPI improvements; Swashbuckle still widely used.

Multiple API versions in Swagger?

One SwaggerDoc per version via IApiVersionDescriptionProvider.

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ASP.NET Core Complete Tutorial (ShopNest)

On this page

Introduction After this article you will Prerequisites Concept deep-dive Hands-on — ShopNest Developer-Facing API Common errors &amp; best practices Interview questions Summary FAQ Swagger in .NET 9? Multiple API versions in Swagger?
Module 1: Foundations
What is ASP.NET Core? Complete Guide Setting Up ASP.NET Core Development Environment ASP.NET Core Project Structure Explained MVC Architecture in ASP.NET Core — Complete Guide Controllers and Actions in ASP.NET Core Routing in ASP.NET Core — Conventional and Attribute Routing Views and Razor Syntax in ASP.NET Core Layouts, Partial Views and View Components Models and ViewModels in ASP.NET Core Forms, Model Binding and Validation in ASP.NET Core Tag Helpers in ASP.NET Core — Complete Guide Static Files, Bundling and Minification in ASP.NET Core
Module 2: Entity Framework Core
Entity Framework Core — Introduction and Setup EF Core Code First — Models, Migrations, Database EF Core CRUD Operations — Create, Read, Update, Delete EF Core LINQ Queries — Beginner to Advanced EF Core Relationships — One-to-One, One-to-Many, Many-to-Many EF Core Fluent API — Advanced Configuration EF Core Repository Pattern and Unit of Work EF Core Performance Optimization Database First Approach with EF Core (Scaffold) EF Core with SQL Server — Advanced Features
Module 3: Dependency Injection & Middleware
Dependency Injection in ASP.NET Core — Complete Guide Middleware in ASP.NET Core — Complete Guide Configuration in ASP.NET Core — appsettings, Environment Variables, Secrets Filters in ASP.NET Core — Action, Authorization, Exception, Resource, Result Logging in ASP.NET Core — ILogger, Serilog, NLog Error Handling and Exception Management in ASP.NET Core
Module 4: Authentication & Security
ASP.NET Core Identity — Complete Setup Guide Authentication in ASP.NET Core — Cookie and JWT Authorization in ASP.NET Core — Roles, Policies, Claims JWT Authentication with Refresh Tokens — Complete Implementation OAuth2 and External Login (Google, Facebook, Microsoft) Data Protection and Encryption in ASP.NET Core HTTPS, SSL Certificates and Security Best Practices
Module 5: Web API
Building REST APIs with ASP.NET Core — Complete Guide API Versioning in ASP.NET Core Swagger / OpenAPI Documentation in ASP.NET Core Input Validation in Web APIs — FluentValidation and Data Annotations Pagination, Filtering and Sorting in ASP.NET Core APIs HTTP Client and Consuming External APIs in ASP.NET Core Minimal APIs in ASP.NET Core .NET 8 SignalR — Real-Time Web Applications
Module 6: Advanced Architecture
Clean Architecture in ASP.NET Core CQRS Pattern with MediatR in ASP.NET Core Repository Pattern — Deep Dive with Generic Repository Background Services and Hosted Services in ASP.NET Core Caching in ASP.NET Core — In-Memory, Distributed, Redis Health Checks in ASP.NET Core AutoMapper in ASP.NET Core Microservices with ASP.NET Core — Introduction Message Queues with RabbitMQ / Azure Service Bus in ASP.NET Core gRPC with ASP.NET Core
Module 7: Testing
Unit Testing ASP.NET Core with xUnit and Moq Integration Testing in ASP.NET Core Testing EF Core — In-Memory vs SQLite Performance Testing and Load Testing ASP.NET Core APIs Test-Driven Development (TDD) in ASP.NET Core
Module 8: Deployment & DevOps
Deploying ASP.NET Core to IIS on Windows Server Docker and Containerization for ASP.NET Core Deploying ASP.NET Core to Azure App Service CI/CD with GitHub Actions for ASP.NET Core Azure SQL Database with ASP.NET Core Environment Configuration and Secrets Management
Module 9: Real-World Projects
Build a Complete Blog Website with ASP.NET Core MVC Build an E-Commerce Product Catalog API (ASP.NET Core Web API) Build a Student Management System (Complete CRUD App) Build a Job Portal (Full Stack ASP.NET Core) Build a REST API with Clean Architecture — Complete Guide Build a Real-Time Chat App with SignalR and ASP.NET Core
Module 10: Advanced Topics
Blazor WebAssembly and Blazor Server — Complete Guide gRPC, GraphQL and Alternative API Styles in ASP.NET Core Rate Limiting and API Throttling in ASP.NET Core .NET 8 Output Caching in ASP.NET Core .NET 8 ASP.NET Core .NET 9 New Features — Complete Guide