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How to Integrate Microsoft 365 Apps with a WinUI 3 Application

Adam Davis Sep 27, 2026 869 views

Question details

The user needs to understand the necessary tools and methodologies for integrating Microsoft 365 services and data into a custom WinUI 3 desktop application.

How to Integrate Microsoft 365 Apps with a WinUI 3 Application

Product: Microsoft 365
Device & OS: Windows
Scenario: Developing a WinUI 3 desktop application that requires access to user data and office applications within the Microsoft 365 ecosystem.
Observed behavior: To achieve seamless data access and application control, developers must implement appropriate APIs like Microsoft Graph and Office JavaScript APIs, alongside proper authentication mechanisms.

Before you start

Ensure you have an active Microsoft 365 developer account, a registered application in Microsoft Entra ID (Azure AD) for authentication, and the Windows App SDK installed for your WinUI 3 project.

Solution 1Recommended

Use Microsoft Graph API for Data and Service Integration

Microsoft Graph is the standard and recommended REST API for accessing Microsoft 365 cloud data, including Outlook emails, calendars, OneDrive files, and Excel workbook data.

Microsoft Graph serves as the unified gateway to data and intelligence in Microsoft 365. By integrating Graph into your WinUI 3 application, you can securely authenticate users and request granular permissions to read or modify their cloud data.

Register the Application

Navigate to the Azure portal and register your WinUI 3 application in Microsoft Entra ID to obtain a client ID. Configure the required Microsoft Graph API permissions (e.g., Mail.Read, Files.ReadWrite) based on your integration needs.

Implement Authentication

Integrate the Microsoft Authentication Library (MSAL) for .NET into your WinUI 3 application to handle secure user sign-in and acquire OAuth 2.0 access tokens.

Install the Microsoft Graph SDK

Open the NuGet Package Manager in Visual Studio and install the 'Microsoft.Graph' package to simplify making authenticated requests to the Graph API endpoints.

Query Microsoft 365 Data

Initialize the GraphServiceClient with your authentication provider. Use the client to make API calls, such as 'graphClient.Me.Messages.GetAsync()' to retrieve Outlook emails or 'graphClient.Me.Drive.GetAsync()' to access OneDrive.

Use Microsoft Graph API for Data and Service Integration

Licensing Requirement: Users authenticating with your application must have valid Microsoft 365 licenses that grant access to the specific services (like Exchange Online or SharePoint) your app is querying.

Solution 2

Implement Office JavaScript APIs for UI and Document Automation

If your WinUI 3 application hosts a WebView2 control or interacts with Office add-ins, use the Office JavaScript APIs to manipulate Word and Excel documents programmatically.

Free Microsoft Office alternative

Looking for a simpler document solution? Try WPS Office

Building custom integrations for Microsoft 365 can be complex and requires expensive licensing. If you or your users simply need a powerful, lightweight, and cost-effective suite for creating and editing documents, spreadsheets, and presentations, WPS Office is an excellent alternative. It offers high compatibility with Microsoft formats without the heavy overhead.

1. Download the Installer: Visit the official WPS Office website and download the free installation package for Windows.
2. Install the Suite: Run the downloaded executable and follow the simple on-screen instructions to install the software.
3. Open Your Files: Launch WPS Office and instantly open your existing Microsoft Office documents with seamless formatting compatibility.

Fully compatible with Microsoft Word, Excel, and PowerPoint file formats (.docx, .xlsx, .pptx).Lightweight installation that runs smoothly on Windows without complex API setups.All-in-one suite design combining Writer, Spreadsheet, Presentation, and PDF tools.Free to use with a familiar, easy-to-navigate user interface that requires no training.

microsoft office alternative - wps office

Frequently Asked Questions

Can I integrate WinUI 3 directly with local desktop Office applications using COM?

Yes, you can use Office Interop assemblies (COM) to automate local desktop installations of Word or Excel from a WinUI 3 app. However, Microsoft Graph is highly recommended for modern, cloud-first Microsoft 365 integration as COM interop is tied to the local machine setup.

Do users need a Microsoft 365 license to use my integrated WinUI 3 app?

Yes, if your application accesses Microsoft 365 services via Microsoft Graph, the authenticated user must have an active Microsoft 365 license that includes those specific services (such as Exchange or OneDrive).

Which is better for OneDrive integration: Microsoft Graph or the legacy OneDrive API?

Microsoft Graph is the current standard and recommended API for integrating OneDrive and all other Microsoft 365 services into custom applications. The legacy OneDrive API is deprecated.

Can I use WinUI 3 to build a native Office Add-in?

Office Add-ins are primarily built using web technologies (HTML, CSS, JavaScript) to run across multiple platforms. However, a WinUI 3 application can interact with a web-based add-in or host it locally using a WebView2 control.

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