Simple Steps to Integrate Swagger UI in a .NET Core Application

Swagger tooling allows you to generate beautiful API documentation, including a UI to explore and test operations, directly from your routes, controllers and models.
Setting it up is simple but requires some code changes.
To enable swagger integration for your .NET Core Web API project you will need to:

  • Install Swashbuckle.AspNetCore package from NuGet
  • Change the Startup.cs class of your Net Core Web API application.
    • Add using statement for OpenApiInfo
    • Modify Configure(IApplicationBuilder app, IWebHostEnvironment env)
    • Modify ConfigureServices(IServiceCollection services)

Changes for Startup.cs

Installing Swagger

From your project folder install the Swagger Nuget package (5.5.1 for this instance)

dotnet add package Swashbuckle.AspNetCore.Swagger --version 5.5.1

Using statement

using Microsoft.OpenApi.Models;

Changes for ConfigureServices()

In the ConfigureServices() method you should add

services.AddSwaggerGen(c =>
    c.SwaggerDoc(v1, new OpenApiInfo
        Title = My Awesome API,
        Version = v1

Changes for Configure()

In the Configure() method you should add

app.UseSwaggerUI(c =>
    c.SwaggerEndpoint(/ swagger / v1 / swagger.json, My Awesome API V1);

I prefer to enable it only for development

if (env.IsDevelopment())
    app.UseSwaggerUI(c =>
        c.SwaggerEndpoint(/ swagger / v1 / swagger.json, My Awesome API V1);

Taking it for a spin

After all these changes, we are finally ready to test our new integration.

dotnet run

Navigate to localhost:4200/swagger to see the SwaggerUI

Note: your port may be different


I prefer my UI’s dark. So, when I am presented with a predominantly white screen from the default theme, I immediately want to change it.
Luckily SwaggerUI supports CSS injection.

Here are the tweaks that we need to make

Enable support for static files


Add folder structure with custom CSS

      └── SwaggerDark.css

Inject custom CSS

Now we can inject the custom CSS with InjectStylesheet()

app.UseSwaggerUI(c =>
    c.SwaggerEndpoint(/ swagger / v1 / swagger.json, MyAPI);
    c.InjectStylesheet(/ swagger - ui / SwaggerDark.css);


Easy, right? We will back with other interesting tutorial. Stay tune!

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