# Building & Using .NET SDKs: A Developer’s Guide

Let’s end this series by doing something powerful: **building a .NET SDK** that others (and your future self) can use in multiple projects.

SDKs make your business logic reusable, testable, and open-source friendly; whether it’s for payments, notifications, or cron parsing.

---

## 🧠 What is a .NET SDK?

An SDK (Software Development Kit) in .NET is typically:
- A **class library** project
- Packaged into a **NuGet** package
- Used across multiple applications
- Published locally or on [NuGet.org](https://nuget.org)

---

## 🛠️ Step 1: Create the SDK Project

```bash
dotnet new classlib -n MyAwesomeSdk
```

Add your logic:

```csharp
public class HelloService
{
    public string Greet(string name) => $"Hello, {name}!";
}
```

---

## 🔁 Step 2: Reference the SDK in Another Project

```bash
dotnet add reference ../MyAwesomeSdk/MyAwesomeSdk.csproj
```

Now you can use it like:

```csharp
var service = new HelloService();
Console.WriteLine(service.Greet("Tunde"));
```

---

## 📦 Step 3: Pack and Publish to NuGet

Add metadata to `.csproj`:

```xml
<PropertyGroup>
  <TargetFramework>net8.0</TargetFramework>
  <PackageId>MyAwesomeSdk</PackageId>
  <Version>1.0.0</Version>
  <Authors>TundeHub</Authors>
  <Description>A simple reusable SDK</Description>
</PropertyGroup>
```

Then:

```bash
dotnet pack -c Release
dotnet nuget push bin/Release/*.nupkg -k YOUR_API_KEY -s https://api.nuget.org/v3/index.json
```

---

## 💡 Best Practices for SDKs

- 🔌 Keep dependencies minimal
- 🧪 Include unit tests in a separate test project
- 📄 Add XML docs and usage examples
- 💬 Use semantic versioning
- 🔐 Avoid hardcoding secrets or connection strings

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## 🧰 Bonus: Open-Source Ready

Create a README like:

```markdown
# MyAwesomeSdk

A lightweight SDK for greeting humans.

## Install

```bash
dotnet add package MyAwesomeSdk
```

## Usage

```csharp
var service = new HelloService();
service.Greet("World");
```
```

Publish to GitHub, tag a release, and you’re official 🎉

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## ✅ Series Complete!

You’ve gone from setup to scaling, from basics to background tasks, from controllers to SDKs.

This isn’t just theory — you’ve built a full, scalable architecture using ASP.NET Core.

📌 Save or bookmark this series  
💬 Share your progress  
🛠 Build something great — and share it with the world

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Let’s keep pushing boundaries, writing clean code, and supporting each other as devs 💙