🔧 Authenticating to SharePoint Online with PnP Core SDK and MSAL in .NET 6+

Author: Edvaldo Guimarães\ Category: Microsoft 365 Development / C# / SharePoint\ Tags: .NET 6, PnP Core SDK, MSAL, SharePoint Online, Authentication

🧠 Introduction

In this article, we’ll explore how to authenticate to SharePoint Online using the PnP Core SDK and MSAL interactive login in a .NET 6+ console application. This is the foundation for building powerful automation tools that interact with SharePoint securely and efficiently.

🛠️ Prerequisites

To follow along, you’ll need:

Visual Studio 2022 with .NET 6 or later
A registered Azure AD App with:
- Client ID
- Tenant ID
- Delegated permission: Sites.ReadWrite.All
Access to a SharePoint Online site

🚀 Implementation

1. Create a Console App

In Visual Studio:

Create a new project → Console App (.NET 6 or higher)
Name it SharePointUploader

2. Install Required NuGet Packages

Install the following packages via NuGet Package Manager:

PnP.Core
PnP.Core.Auth

These packages provide access to SharePoint Online and authentication via MSAL.

3. Final Working Code

using System;
using System.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using PnP.Core.Auth;
using PnP.Core.Services;

class Program
{
    static async Task Main(string[] args)
    {
        var services = new ServiceCollection();

        string clientId = "YOUR_CLIENT_ID";
        string tenantId = "YOUR_TENANT_ID";
        string siteUrl = "https://YOUR_DOMAIN.sharepoint.com/sites/YOUR_SITE";

        // Register PnP Core SDK services
        services.AddPnPCore();
        services.AddPnPCoreAuthentication();

        // Register interactive authentication provider
        services.AddScoped&lt;IAuthenticationProvider&gt;(sp =&gt;
            new InteractiveAuthenticationProvider(
                clientId,
                tenantId,
                new Uri("http://localhost")
            )
        );

        var serviceProvider = services.BuildServiceProvider();
        var contextFactory = serviceProvider.GetRequiredService&lt;IPnPContextFactory&gt;();

        using var context = await contextFactory.CreateAsync(siteUrl);

        Console.WriteLine("✅ Successfully connected to SharePoint!");
    }
}

✅ What This Code Does

Sets up dependency injection for PnP Core SDK
Uses MSAL for interactive login
Connects to a SharePoint Online site using the provided URL
Prints a success message once connected

🔄 What’s Next?

In the next article, we’ll extend this app to:

List files modified in the last hour from a local directory
Upload those files as attachments to a specific item in a SharePoint list

This will turn your app into a practical automation tool for document tracking and integration with Microsoft 365.

📌 Conclusion

Using the PnP Core SDK with MSAL interactive login is a modern, secure, and scalable way to connect to SharePoint Online. This approach aligns with Microsoft’s best practices and prepares your app for future enhancements