What is Minimal API in .NET Core and How to Create this step by step

What is Minimal API in .NET?

Minimal API is a lightweight way to build HTTP APIs in .NET (introduced in .NET 6).

It allows you to create REST APIs with less code, without Controllers, Startup class, or complex structure.

👉 Best for:

• Microservices
• Small REST APIs
• Backend for Angular/React apps

🔥 Traditional API vs Minimal API

Traditional ASP.NET Core	Minimal API
Uses Controllers	No Controllers
Uses Startup.cs	No Startup.cs
More boilerplate code	Very less code
Better for large apps	Best for small/medium APIs

Step by Step Implementation

1. Create .NET Core API based Project
2. Go into Program.cs
3. Write only this code

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.MapGet("/", () => "Hello World!");

app.Run();

4. Run the application

Step by Step CRUD Operation (Minimal API)

Install Swagger Package: Swashbuckle.AspNetCore

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

List<Student> students = new()
{
    new Student(1, "Shiva", 22),
    new Student(2, "Rahul", 23)
};

// GET all students
app.MapGet("/students", () => students);

// GET by ID
app.MapGet("/students/{id}", (int id) =>
{
    var student = students.FirstOrDefault(s => s.Id == id);
    return student is not null ? Results.Ok(student) : Results.NotFound();
});

// POST
app.MapPost("/students", (Student student) =>
{
    students.Add(student);
    return Results.Created($"/students/{student.Id}", student);
});

// PUT
app.MapPut("/students/{id}", (int id, Student updatedStudent) =>
{
    var student = students.FirstOrDefault(s => s.Id == id);
    if (student is null)
        return Results.NotFound();

    students.Remove(student);
    students.Add(updatedStudent);

    return Results.Ok(updatedStudent);
});

// DELETE
app.MapDelete("/students/{id}", (int id) =>
{
    var student = students.FirstOrDefault(s => s.Id == id);
    if (student is null)
        return Results.NotFound();

    students.Remove(student);
    return Results.Ok();
});

app.Run();

public record Student(int Id, string Name, int Age);