Minimal APIs vs Controllers: A Real Comparison

When building an API with ASP.NET Core, one of the first architectural decisions you may face is whether to use Minimal APIs or the traditional Controller-based approach.

Both options can be used to build fast, reliable and maintainable APIs. Both support dependency injection, authentication, authorisation, middleware, model binding and validation. Both can also be used to build production-ready applications.

The real difference is not whether one approach is capable and the other is not. The difference is how they organise your application and how much structure they provide as your project grows.

Minimal APIs are designed to reduce the amount of code and ceremony required to create HTTP endpoints. Controllers, on the other hand, provide a more structured programming model that has been used in ASP.NET Core applications for many years.

So, which one should you choose?

The answer depends largely on the size and complexity of your application.

What Are Minimal APIs?

Minimal APIs were introduced with ASP.NET Core 6 as a simpler way to create HTTP APIs. Instead of creating a Controller class with action methods and attributes, you define your endpoints directly in your application.

A simple Minimal API might look something like this:

var builder = WebApplication.CreateBuilder(args);

var app = builder.Build();

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

app.Run();

The endpoint is mapped directly to the HTTP GET request. There is no Controller class, no action method and no routing attributes required.

This makes Minimal APIs very attractive when you need to create a small API quickly.

The code is easy to read because the route and the implementation are located close together. For a small application, this can make the entire project easier to understand.

However, the simplicity that makes Minimal APIs attractive for smaller projects can become less obvious when the number of endpoints increases.

What Are Controllers?

Controllers are the traditional approach to building APIs with ASP.NET Core.

A Controller groups related endpoints into a class. Individual methods within the class represent actions that respond to HTTP requests.

For example, the same API could be written using a Controller:

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

        return Ok(products);
    }
}

The Controller provides a clear structure for organising related functionality.

As the application grows, you can have a ProductsController for products, an OrdersController for orders and a CustomersController for customers.

This approach creates a predictable structure that many developers find easy to navigate, particularly when working on larger applications or within a development team.

Minimal APIs Are Simpler

One of the biggest advantages of Minimal APIs is their simplicity.

If you need to create a small API with a handful of endpoints, using Controllers can sometimes feel like unnecessary ceremony. You may need to create several classes and configure additional services before you can start writing your actual endpoint logic.

Minimal APIs allow you to get started with considerably less code.

For example, if you are creating a small internal service, a microservice or a lightweight API for a specific purpose, Minimal APIs can be an excellent choice.

The route is defined directly alongside the code that handles the request, making the implementation easy to understand.

This can also make Minimal APIs particularly appealing for developers who want to build small, focused services without introducing a large amount of infrastructure.

Controllers Provide More Structure

The biggest advantage of Controllers is structure.

A well-organised Controller-based API provides a familiar pattern for developers. Related functionality is grouped together, and the framework provides a clear set of conventions for routing, action methods, filters and responses.

This can become increasingly valuable as an application grows.

Imagine an API with hundreds of endpoints. Having all those endpoints defined directly in a small number of files could quickly become difficult to manage.

Controllers allow you to divide the application into logical areas.

A ProductsController can contain product-related operations, while an OrdersController handles orders. This makes it easier to locate functionality and understand how the API is organised.

For larger applications, this additional structure can be a significant benefit.

Readability and Maintainability

At first glance, Minimal APIs often appear to be more readable because there is less code.

For a small application, this is usually true.

The problem is that an API rarely stays small forever.

As more endpoints are added, the code can become increasingly difficult to navigate if the application is not carefully structured.

The good news is that Minimal APIs do not have to mean putting everything inside Program.cs. Endpoints can be moved into separate classes and extension methods, allowing you to create a more organised architecture while still using the Minimal API programming model.

Controllers naturally encourage this separation because each Controller is already a dedicated class.

This means Controllers can have an advantage when maintainability and long-term organisation are important considerations.

The real lesson is that neither approach automatically produces clean code. Good architecture still matters regardless of whether you choose Minimal APIs or Controllers.

Dependency Injection

Both approaches work well with dependency injection.

With Minimal APIs, dependencies can be injected directly into endpoint parameters.

For example:

app.MapGet("/api/products", async (IProductService productService) =>
{
    var products = await productService.GetProductsAsync();

    return Results.Ok(products);
});

The framework can resolve the IProductService dependency and provide it to the endpoint.

With Controllers, dependencies are commonly injected through the constructor:

public class ProductsController : ControllerBase
{
    private readonly IProductService _productService;

    public ProductsController(IProductService productService)
    {
        _productService = productService;
    }
}

Both approaches are perfectly capable of supporting dependency injection.

The difference is largely in how the dependency is expressed.

Minimal APIs can make simple dependencies very concise, while Controllers provide a more traditional class-based structure that some developers may find easier to understand in larger applications.

Routing

Routing is another area where both approaches are capable.

Minimal APIs define routes using methods such as MapGet, MapPost, MapPut and MapDelete.

For example:

app.MapGet("/api/products/{id}", (int id) =>
{
    return Results.Ok(id);
});

Controllers typically use attributes:

[HttpGet("{id}")]
public IActionResult GetProduct(int id)
{
    return Ok(id);
}

Both approaches allow you to create complex routing structures.

Minimal APIs make the route definition immediately visible, while Controllers separate the routing information from the application's startup configuration.

For simple APIs, Minimal API routing can feel more direct. For larger APIs, the conventions provided by Controllers can make the overall routing structure easier to manage.

Validation

Validation is an important consideration when building real-world APIs.

Controllers have traditionally provided a straightforward model-binding and validation experience through features such as the ApiController attribute.

For example, you can define a request model with validation attributes and allow ASP.NET Core to automatically handle invalid requests.

Minimal APIs can also support validation, but the experience has historically been less automatic than the traditional Controller approach. Modern versions of ASP.NET Core have continued to improve Minimal API capabilities, but Controllers can still feel more familiar when working with complex request models and validation requirements.

If your API contains a large number of complex forms and request models, this may be an area where Controllers provide a more comfortable development experience.

Filters and Cross-Cutting Concerns

Controllers have a mature system of filters that can be used for cross-cutting concerns.

Action filters, authorization filters and exception filters can be used to apply behaviour around Controller actions.

Minimal APIs take a different approach.

Endpoint filters can be used with Minimal APIs to perform similar tasks, such as validation, logging or other processing before and after an endpoint executes.

Both approaches can support cross-cutting concerns, but Controllers have been around for longer and many developers are more familiar with their filter-based architecture.

Minimal APIs are catching up quickly, but Controllers can still feel more natural for applications that make extensive use of filters.

Performance

Performance is often mentioned when comparing Minimal APIs and Controllers.

Minimal APIs were designed with a lightweight programming model, and they can have lower overhead in some scenarios.

However, this does not mean that Controllers are slow.

For most business applications, database queries, network calls and external services will have a much greater impact on performance than whether an API uses Minimal APIs or Controllers.

In a typical application, the difference between the two approaches is unlikely to be the deciding factor.

Choosing an architecture based purely on theoretical performance improvements can lead to poor decisions.

It is usually more important to choose the approach that makes your application easier to build, test and maintain.

Testing

Both Minimal APIs and Controllers can be tested effectively.

Controllers are often straightforward to unit test because they are classes with methods that can be called directly.

Minimal API endpoint logic can also be tested, particularly when the application follows good separation-of-concerns principles.

The important point is that your business logic should not be tightly coupled to your HTTP endpoints.

Whether you use Controllers or Minimal APIs, your core application logic should ideally live in services or application layers that can be tested independently.

This is particularly important for larger applications where maintainability and automated testing are priorities.

When Minimal APIs Make Sense

Minimal APIs are an excellent choice for small and focused applications.

They work particularly well for simple REST APIs, microservices, internal services and applications where you want to minimise unnecessary ceremony.

They are also a good option when you want to create an API quickly and the number of endpoints is relatively small.

For developers who prefer a lightweight approach, Minimal APIs can be a refreshing alternative to the more traditional Controller model.

They can also work very well with modern architectural approaches, provided the application is structured correctly.

When Controllers Make Sense

Controllers are often the better choice for larger and more complex applications.

If your API contains many endpoints, complex validation requirements, extensive use of filters or a large development team, the structure provided by Controllers can make the project easier to manage.

Controllers also provide a familiar programming model for developers who have worked with ASP.NET MVC or earlier versions of ASP.NET Core.

For enterprise applications where consistency and established conventions are important, Controllers remain a strong option.

There is also nothing wrong with choosing Controllers simply because your development team prefers them.

Technology decisions should be based on the needs of the project rather than following trends.

Can You Use Both?

One of the most useful things to remember is that you do not necessarily have to choose one approach exclusively.

ASP.NET Core allows you to use Minimal APIs and Controllers within the same application.

This means you could use Controllers for the main part of a large application while using a Minimal API endpoint for a small, specialised requirement.

For example, a health check or simple status endpoint may be perfectly suited to a Minimal API, while your main business functionality could remain organised within Controllers.

This hybrid approach can sometimes provide the best of both worlds.

However, mixing approaches should be done for a clear reason. Introducing multiple programming models without a good architectural justification can also make an application more complicated.

Minimal APIs vs Controllers: The Real Comparison

The real comparison is not about which approach is universally better.

Minimal APIs are about reducing ceremony and making simple APIs easier to build. Controllers are about providing structure and conventions that can help organise larger applications.

For a small API with a few endpoints, Minimal APIs can be a fantastic choice. They allow you to write less code and get an application running quickly.

For a larger API with complex business requirements, Controllers may provide a clearer structure and a more familiar development experience.

The most important consideration is the application you are actually building.

Choosing Minimal APIs because they are newer does not automatically make them better. Likewise, choosing Controllers simply because they are familiar does not mean they are always the right solution.

My Verdict

For small APIs, microservices and lightweight services, I would seriously consider Minimal APIs. They are clean, modern and can significantly reduce the amount of boilerplate code required.

For larger applications with many endpoints and complex requirements, I would generally lean towards Controllers because the additional structure can make the application easier to navigate and maintain.

However, I would not consider either approach to be the clear winner.

Minimal APIs and Controllers are both valuable tools in the ASP.NET Core ecosystem. The best choice is the one that fits the size, complexity and long-term requirements of your application.

Ultimately, good architecture is more important than the choice between Minimal APIs and Controllers. A well-designed application with clear separation of concerns, sensible dependency injection and maintainable business logic can be successful using either approach.

The real question is not "Which one is better?"

It is "Which one makes the most sense for this application?"