Minimal APIs vs Controllers in .NET: When to Choose Each

ASP.NET Core offers multiple ways to build web APIs, with Minimal APIs and Controllers being the two primary approaches. Since the introduction of Minimal APIs in .NET 6, many developers have questioned whether controllers are becoming obsolete. The answer is no. Both approaches are actively supported and serve different purposes.

Choosing the right option depends on your application's complexity, team size, and long-term maintenance requirements. In this article, we'll compare Minimal APIs and Controllers, explore their strengths and limitations, and discuss when each approach is the better choice.

Understanding Minimal APIs

Minimal APIs provide a lightweight way to create HTTP endpoints with minimal configuration. They eliminate much of the boilerplate associated with traditional controllers, making them ideal for simple services and microservices.

A basic Minimal API looks like this:

var builder = WebApplication.CreateBuilder(args);

var app = builder.Build();

app.MapGet("/products", () =>
{
    return Results.Ok(new[]
    {
        new { Id = 1, Name = "Laptop" },
        new { Id = 2, Name = "Keyboard" }
    });
});

app.Run();

With just a few lines of code, the application exposes a REST endpoint without requiring controller classes or attributes.

Understanding Controllers

Controllers follow the MVC pattern and organize endpoints into dedicated classes. They provide a structured approach that scales well for larger applications.

Example:

[ApiController]
[Route("api/products")]
public class ProductsController : ControllerBase
{
    [HttpGet]
    public IActionResult GetProducts()
    {
        return Ok(new[]
        {
            new { Id = 1, Name = "Laptop" },
            new { Id = 2, Name = "Keyboard" }
        });
    }
}

Controllers separate routing, business logic, and request handling, making applications easier to maintain as they grow.

Key Differences

Feature	Minimal APIs	Controllers
Boilerplate	Very Low	Moderate
Learning Curve	Easy	Moderate
Best for	Small APIs, microservices	Large applications
Attribute Routing	Limited	Extensive
API Organization	Endpoint-based	Class-based
Dependency Injection	Supported	Supported
Model Validation	Manual or endpoint filters	Built-in
Filters	Endpoint filters	Action filters

Minimal APIs prioritize simplicity, while Controllers emphasize structure and flexibility.

Performance Considerations

Minimal APIs have a slightly smaller request processing pipeline because they avoid some MVC infrastructure. For lightweight endpoints, this can result in marginally lower overhead.

However, for most business applications, the difference is negligible. Database access, network latency, and business logic typically have a much greater impact on performance than the framework choice.

Choose the approach that improves maintainability rather than focusing solely on micro-optimizations.

When to Choose Minimal APIs

Minimal APIs are a great choice when:

Building microservices
Creating internal APIs
Developing proof-of-concept applications
Exposing simple CRUD endpoints
Building serverless HTTP functions

They allow developers to create APIs quickly with minimal setup.

Example with dependency injection:

app.MapGet("/products/{id}", async (
    int id,
    IProductRepository repository) =>
{
    var product = await repository.GetByIdAsync(id);

    return product is null
        ? Results.NotFound()
        : Results.Ok(product);
});

This approach keeps endpoint definitions concise while still supporting dependency injection.

When to Choose Controllers

Controllers are better suited for applications that require:

Complex business logic
Large development teams
Extensive validation
API versioning
Authorization policies
Custom filters
Well-organized codebases

They encourage separation of concerns and make applications easier to extend over time.

Validation Differences

Controllers provide automatic model validation when using the [ApiController] attribute.

[HttpPost]
public IActionResult Create(ProductDto product)
{
    if (!ModelState.IsValid)
        return BadRequest(ModelState);

    return Ok();
}

Minimal APIs can also validate input but typically require additional code or endpoint filters for advanced validation scenarios.

For applications with many request models, Controllers often provide a more streamlined validation experience.

Maintainability Considerations

Small projects benefit from the simplicity of Minimal APIs, but as applications grow, placing many endpoints inside Program.cs can reduce readability.

A common practice is to group Minimal API endpoints into extension methods or separate endpoint classes.

Controllers naturally organize related endpoints into dedicated classes, making navigation and maintenance easier for larger projects.

Best Practices

Choose Minimal APIs for lightweight services and microservices.
Use Controllers for enterprise applications with complex business logic.
Keep business logic outside endpoints or controllers.
Register dependencies through the built-in dependency injection container.
Use asynchronous programming for database and network operations.
Organize endpoints logically to improve readability.
Focus on maintainability over minor performance differences.

Common Mistakes

Assuming Minimal APIs Replace Controllers

Minimal APIs complement Controllers—they don't replace them. Both are fully supported and suitable for different scenarios.

Putting Business Logic in Endpoints

Endpoints should coordinate requests, not contain business rules. Move business logic into services to improve testability and maintainability.

Choosing Based Only on Performance

Although Minimal APIs have slightly lower framework overhead, the performance difference is rarely significant in real-world applications.

Mixing Patterns Inconsistently

Using both approaches within the same application is possible, but establish clear architectural guidelines so the codebase remains consistent.

Conclusion

Minimal APIs and Controllers are both excellent options for building ASP.NET Core applications. Minimal APIs excel in simplicity, making them ideal for microservices, lightweight APIs, and rapid development. Controllers provide a structured, feature-rich framework that scales well for complex enterprise applications.

Rather than viewing one approach as a replacement for the other, consider the size, complexity, and future growth of your project. For small, focused services, Minimal APIs offer an elegant solution. For applications requiring advanced routing, validation, filters, and long-term maintainability, Controllers remain the preferred choice.

Ultimately, selecting the right approach is less about performance and more about choosing the architecture that best supports your team's productivity and your application's long-term success.