Minimal APIs at Scale

Enterprise-Ready Minimal APIs in .NET: Scaling Simplicity

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Overview

This repository contains the finished demo code from my presentation Minimal APIs at Scale.

I live-coded parts of the CustomerEndpoints to show how Minimal APIs evolve from a simple Weather example in Program.cs into a structured, enterprise-ready API.

This repo includes the complete, working version of that code.

You’ll see:

• How to structure Minimal APIs with extension methods
• Using DTOs (CustomerRequest, CustomerResponse) to separate contracts from entities
• Built-in validation in .NET 10
• Consistent error handling with endpoint filters
• Returning strong responses with TypedResults and CreatedAtRoute
• Configuring OpenAPI + Scalar via extension methods

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Project Structure

.
├── Endpoints/
│   └── Customer/
│       └── CustomerEndpoints.cs
├── Extensions/
│   └── OpenApiExtensions.cs
├── Filters/
│   └── ExceptionHandlingFilter.cs
├── Models/
│   ├── Customer.cs
│   └── DTO/
│       ├── CustomerRequest.cs
│       └── CustomerResponse.cs
├── Services/
│   ├── ICustomerService.cs
│   └── CustomerService.cs
├── Program.cs
└── <project>.csproj

• Endpoints/Customer/ – Customer-specific endpoints via extension methods (app.MapCustomerEndpoints()).

• Extensions/ – Application configuration helpers (e.g., ConfigureOpenApi, MapScalar).

• Filters/ – Cross-cutting concerns (e.g., exception handling).

• Models/ – Entities and DTOs (request/response contracts).

• Services/ - Business logic implementation for ICustomerService.

• Program.cs – Application entry point (minimal setup, delegates to extensions)

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Running the App

Prerequisites

• Visual Studio 2026 or the .NET CLI

• .NET 10 SDK RC1 installed.

Check your installed SDKs with:

dotnet --list-sdks

You should see something like:

10.0.xxx [C:\Program Files\dotnet\sdk]

Clone the Repo

git clone https://github.com/CoderFoundry/commityourcode-minimal-api.git
cd commityourcode-minimal-api

Run the App

1. Open the solution in Visual Studio 2026
2. Press F5 or (ctril+F5) to run.

You can also use Visual Studio Code to open the project and use the .NET CLI

To run the app using the CLI

dotnet run

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Explore the API

Once running, open Scalar (API reference UI):
http://localhost:7022/

• If you’re running from Visual Studio 2026, it should launch automatically in your browser.
• If not, you may need to adjust your launchSettings.json file under Properties/ to adjust the port settings.
• If you’re running from the CLI, open the URL manually (port may vary based on your local environment).

When the app is running, you should see a Customers dropdown with the three endpoints:

• GET /customers
• GET /customers/{id}
• POST /customers

Endpoints

• GET /customers → Returns all customers

• GET /customers/{id} → Returns a customer by ID

• POST /customers → Creates a new customer (with validation)

Each endpoint delegates business logic to ICustomerService, keeping handlers lean and maintainable.
You can see the full implementation in:
Services/CustomerService.cs

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About the Demo

During my talk, I showed:

1. Weather endpoint in Program.cs (simple example from Microsoft).

2. Moving Customers into CustomerEndpoints.cs via extension methods.

3. Adding app.MapCustomerEndpoints(); to keep Program.cs clean.

4. Live-coding the POST /customers endpoint.

This repo contains the finished version so that you can run everything end-to-end without modification.

Learn More

Want to go deeper into .NET, Blazor, and API patterns? 👉 learn.coderfoundry.com

License

MIT License – free to use, share, and adapt.