Advanced Swagger Use Cases in ASP.NET Core (.NET 6/7/8)

After setting up Swagger for basic API documentation, I realized there's so much more you can do with it — especially in real-world projects. Grouping endpoints, supporting versioning, securing Swagger with JWT, and even hiding endpoints when needed — these advanced use cases have made my development workflow smoother and more professional.

In this article, I’m sharing the Swagger features I actually use in .NET 6, 7, and 8 projects — along with code snippets, tips, and things to avoid.

📚 1. Grouping Endpoints (Using Tags)

Sometimes your Swagger UI becomes overwhelming with too many endpoints. Grouping them into logical sections makes it easier to navigate.

🔧 Option 1. Group by controller name (default)

This happens automatically, but you can customize it further.

🔧 Option 2. Use `[ApiExplorerSettings(GroupName = "v1")]`

Or use SwaggerDoc and define multiple groups.

// Program.cs 
builder.Services.AddSwaggerGen(c => 
{ 
    c.SwaggerDoc("v1", new OpenApiInfo { Title = "My API V1", Version = "v1" }); 
    c.SwaggerDoc("v2", new OpenApiInfo { Title = "My API V2", Version = "v2" }); 
}); 

// Controller 
[ApiExplorerSettings(GroupName = "v2")] 
[Route("api/v2/[controller]")] 
public class OrdersController : ControllerBase 
{ 
    //... 
}

Now, Swagger UI will show v1 and v2 as tabs.

🔄 2. API Versioning in Swagger

If your app supports multiple API versions, Swagger should reflect that. Here’s how to set it up.

✅ Step 1. Add required NuGet packages

dotnet add package Microsoft.AspNetCore.Mvc.Versioning 
dotnet add package Microsoft.AspNetCore.Mvc.Versioning.ApiExplorer

✅ Step 2. Configure versioning

builder.Services.AddApiVersioning(options => 
{ 
    options.ReportApiVersions = true; 
    options.AssumeDefaultVersionWhenUnspecified = true; 
    options.DefaultApiVersion = new ApiVersion(1, 0); 
}); 

builder.Services.AddVersionedApiExplorer(options => 
{ 
    options.GroupNameFormat = "'v'VVV"; 
    options.SubstituteApiVersionInUrl = true; 
});

✅ Step 3. Update SwaggerGen

builder.Services.AddSwaggerGen(); 
builder.Services.ConfigureOptions<ConfigureSwaggerOptions>();

(You’ll need to create a ConfigureSwaggerOptions class — I can generate this for you if needed.)

🔐 3. Add JWT Authentication to Swagger UI

If you're using JWT Bearer tokens, you can allow Swagger to send them in request headers.

✅ Configure Swagger with Security Definitions

builder.Services.AddSwaggerGen(c => 
{ 
    c.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme 
    { 
        Description = "Enter 'Bearer' followed by your JWT token.", 
        Name = "Authorization", 
        In = ParameterLocation.Header, 
        Type = SecuritySchemeType.ApiKey, 
        Scheme = "Bearer" 
    }); 

    c.AddSecurityRequirement(new OpenApiSecurityRequirement 
    { 
        { 
            new OpenApiSecurityScheme 
            { 
                Reference = new OpenApiReference 
                { 
                    Type = ReferenceType.SecurityScheme, 
                    Id = "Bearer" 
                } 
            }, 
            Array.Empty<string>() 
        } 
    }); 
});

Now Swagger UI will show an Authorize button at the top where you can paste your token.

🙈 4. Hiding Specific Endpoints from Swagger

Sometimes you don’t want every endpoint exposed in Swagger, especially internal or admin-only APIs.

🔧 Option. Use `[ApiExplorerSettings(IgnoreApi = true)]`

[ApiExplorerSettings(IgnoreApi = true)] 
[HttpGet("internal-only")] 
public IActionResult HiddenEndpoint() 
{ 
    return Ok("This won't appear in Swagger"); 
}

Works at both the action and controller level.

📤 5. Export Swagger JSON/YAML

You can share your API contract with clients or import it into tools like Postman or Azure API Management.

JSON endpoint:
https://localhost:5001/swagger/v1/swagger.json
YAML: You’ll need a separate generator, or use tools like Swagger Editor or SwaggerHub to convert JSON to YAML.

📝 6. Improve Models with DataAnnotations

Swagger auto-generates schemas from your models. Enhance them with [Required], [StringLength], and summaries.

public class ProductDto 
{ 
    [Required] 
    [StringLength(50)] 
    public string Name { get; set; } 

    /// <summary>Product price in USD</summary> 
    public decimal Price { get; set; } 
}

Make sure XML comments are enabled to see them in the UI.

🎨 7. UI Customizations (Logo, Layout, etc.)

You can style Swagger UI by injecting CSS or JS.

app.UseSwaggerUI(c => 
{ 
    c.InjectStylesheet("/swagger-ui/custom.css"); 
    c.DocumentTitle = "My API Docs"; 
});

Use this to:

Add your company logo
Change the default collapsed/expanded state
Customize font/colors

🚀 Best Practices I Follow

Practice	Why It Matters
Group endpoints and support versioning	Helps clients consume APIs reliably
Secure Swagger UI with tokens or roles	Avoids exposing sensitive endpoints
Use meaningful model annotations	Improves documentation quality
Keep Swagger in sync with real behavior	Prevents confusion for API consumers
Don’t expose internal/test-only APIs	Keeps docs clean and production-safe

👋 Conclusion

When you go beyond the basics, Swagger becomes a powerful tool, not just for docs, but for API governance and developer experience. These advanced use cases have helped me a lot when working with large APIs and teams.

If you’re already using Swagger in your .NET app, I highly recommend trying out a few of these. They’re not hard to implement, and the payoff is worth it.