Introduction
Microsoft has announced the official retirement of the SharePoint Add-In extensibility model in SharePoint Online, signaling a major shift toward modern customization practices within the Microsoft 365 platform. This change directly impacts organizations currently using “SharePoint Add-Ins” (formerly known as the SharePoint App model) to extend functionality.
The retirement is being phased:
- November 1, 2024: Add-Ins will be blocked in new Microsoft 365 tenants.
- April 2, 2026: SharePoint Add-Ins will cease to the function in all existing Microsoft 365 tenants.
After this final cutoff, any custom solution built as a SharePoint-Hosted or Provider-Hosted add-in will be disabled. This affects all clouds (Commercial, Government, DoD) and related services like Project Online.
This transition is part of Microsoft’s strategy to embrace more secure, performance, and modern customization approaches. The SharePoint Framework (SPFx), which is the current preferred and actively supported model for extending SharePoint, is not affected by this retirement. The underlying infrastructure for Add-Ins, specifically Azure ACS (Access Control Services) used for external add-in authentication, has already been deprecated, driving the need for this platform consolidation.
For developers, consultants, and IT decision-makers, this is an urgent call to action. You must immediately assess all in-use SharePoint Add-Ins and begin planning their replacement. This article will detail the reasons for the retirement, explore viable migration options, outline strategic planning considerations, and provide concrete action steps for a smooth transition before the 2026 deadline.
🎯 Why SharePoint Add-Ins are Being Retired
The move to sunset SharePoint Add-Ins is driven by Microsoft’s commitment to delivering a modernized SharePoint experience. The key factors include:
- Modernization and User Experience: Introduced in the SharePoint 2013 era, Add-Ins are now considered dated. They often run in isolated contexts, such as iframes or separate sub-sites (app webs), which leads to a disjointed user experience. Microsoft is prioritizing modern frameworks like SPFx that integrate seamlessly and natively into the SharePoint UI, offering a faster and more consistent look and feel across SharePoint and Teams.
- Performance and Security: The Add-In model relies on Azure Access Control Services (ACS), a legacy authentication system that Microsoft has retired across its broader ecosystem and is now retiring within SharePoint Online. Retiring Add-Ins allows the platform to remove these legacy components, which reduces security vulnerabilities and performance overhead. Newer models use modern Azure AD/Microsoft Entra ID authentication and maintained technology stacks, keeping the platform more efficient.
- Customer Adoption of Modern Solutions: Over the last few years, the community has overwhelmingly adopted the SharePoint Framework (SPFx) as the dominant customization model. By retiring the legacy Add-In model, Microsoft can focus its investment on modern tools (SPFx, Power Platform, Teams apps) that customers are already utilizing, simplifying the ecosystem and development guidance.
- Simplifying the Ecosystem: Maintaining multiple parallel extensibility models creates administrative complexity. Deprecating Add-Ins streamlines the platform. Furthermore, Microsoft has already simplified the marketplace by stopping acceptance of new Add-Ins as of March 1, 2024, and blocking acquisition of all Add-Ins from the public marketplace after July 1, 2024, steering customers toward SPFx solutions.
In essence, the retirement is an effort to unify and modernize the extensibility story, ensuring all new development is on a supported, integrated, and future-proof path.
🔁 Migration Options and Modern Alternatives
The migration path for a SharePoint Add-In depends on its original structure and functionality. Robust modern alternatives exist to achieve the same business goals.
1. SharePoint-Hosted Add-Ins SharePoint Framework (SPFx)
SharePoint-hosted add-ins have their components (lists, pages, scripts) residing in a special “app web” within SharePoint and typically surface simple UI elements.
- Recommended Alternative: Rebuild the functionality using SPFx Web Parts or Extensions.
- Why SPFx? SPFx components run client-side (JavaScript/TypeScript) directly within the modern SharePoint page context, eliminating the need for iframes and offering seamless integration. They securely interact with SharePoint data using modern REST or Microsoft Graph APIs.
- Crucial Step: You must retrieve any data stored in the add-in’s isolated “app web” and migrate it to a standard SharePoint list or another data source before uninstalling the add-in, as uninstallation will permanently delete the app web and all its contents.
2. Provider-Hosted Add-Ins Standalone Apps + Microsoft 365 Integration
Provider-hosted add-ins involve an external web application (e.g., hosted in Azure) that interacts with SharePoint, typically using Azure ACS for authentication.
- Recommended Alternative: Rearchitect the solution as a standalone web application (SaaS) utilizing modern authentication (OAuth with Microsoft Entra ID) instead of the deprecated ACS.
- Integration: The standalone app can be surfaced to users via:
- An independent web URL.
- A Microsoft Teams app or tab.
- An SPFx Web Part that serves as a front-end UI and securely calls the external application’s APIs.
- Key Shift: The authentication model must transition from the legacy ACS tokens to modern Azure AD (Entra ID) app registration and OAuth flows. The new solution effectively becomes a regular SaaS application that leverages Microsoft 365 APIs.
3. Other Alternatives: Power Platform or Built-In Features
For simpler use cases, custom code may no longer be necessary:
- Forms/Workflows: Replace add-ins that handle forms or simple processes with a Power App or a Power Automate flow.
- Content/Widgets: Check if modern SharePoint or Teams offers an out-of-the-box feature or web part (e.g., modern list forms, built-in planner integrations) that already provides the functionality.
The choice should align the business purpose of the original add-in with the most efficient modern alternative.
🛠️ Strategic Planning and Action Steps
Migrating Add-Ins requires a strategic approach encompassing assessment, resource allocation, and change management.
Strategic Considerations
- Assess Impact and Criticality: Identify all deployed Add-Ins and map them to the business processes they support. Prioritize migration efforts based on which add-ins are mission-critical or widely used.
- Inventory and Data Retention: Use the Microsoft 365 Assessment Tool to scan your tenant and generate a Power BI report detailing Add-In usage, installation sites, and ACS principal details. Crucially, plan to retrieve and migrate data from any SharePoint-hosted add-in’s app web before it is removed.
- Third-Party Vendors: Contact vendors for any commercially acquired Add-Ins to inquire about their SPFx or Microsoft 365 App replacement plans. Most major ISVs are already offering modern alternatives.
- Resource Planning and Skills: Allocate sufficient time and budget for development. Ensure your team or partners have the necessary SPFx expertise.
- Governance: Stop New Investment: Consider using PowerShell ( `
Set-SPOTenant -IsSharePointAddInsDisabled $true` ) to disable the installation of new SharePoint Add-Ins at the tenant level. This prevents accidental investment in a deprecated technology, while existing add-ins remain functional until 2026. - User Communication: Implement a change management plan for user-facing solutions. Frame the migration as an upgrade that delivers a better, more modern user experience.
Concrete Action Checklist
| Step | Detail |
| 1. Inventory | Run the Microsoft 365 Assessment Tool to get a complete list of all deployed Add-Ins and their details. |
| 2. Prioritize | Classify each Add-In: Retire, Replace with SPFx, Replace with Standalone App/Power Platform, or Update Third-Party. Assign priority based on business criticality. |
| 3. Plan Replacements | Design the new modern solution (e.g., architecture, SPFx components, Azure AD app registrations). Plan the data migration strategy from old app webs. |
| 4. Develop & Test | Build the new SPFx web parts, extensions, or standalone apps. Thoroughly test functionality, security, and performance, ideally running the new solution in parallel with the old. |
| 5. Deploy & Migrate Data | Deploy the new solution to production. Perform the data migration from the old Add-In’s data store to the new system. |
| 6. Decommission Legacy | Once the new solution is stable, uninstall the old SharePoint Add-Ins. Be meticulous with this step to ensure all required data has been successfully migrated first. |
| 7. Finalize by 2026 | Aim to complete all critical migrations well before April 2, 2026, ensuring zero reliance on the deprecated model when the final cutoff occurs. |
By following these steps, you can systematically retire your SharePoint Add-Ins and transition to modern equivalents. The key is to start early and tackle the project in manageable phases. This not only mitigates the risk of service interruption but also spreads the work over time. Many organizations have successfully gone through similar transitions (for example, moving from classic SharePoint to modern, or from InfoPath to Power Apps); the pattern is similar here: inventory, plan, replace, and decommission. With proper planning, the 2026 retirement deadline will be a milestone you’re ready for, rather than a crisis.
Conclusion (Friendly Reminder)
Change can be challenging, but it often comes with opportunity. The retirement of SharePoint Add-Ins is a push towards embracing newer, better technologies in the Microsoft 365 ecosystem. By acting now, you’re not only avoiding a last-minute scramble in 2026, but also delivering more value to your users through modern solutions. Start the conversation in your team about this transition – the sooner you formulate a plan, the smoother the road ahead will be. Microsoft and the community are providing guidance and tools to help, so you’re not alone in this journey. Good luck with your migration efforts, and here’s to a future of SharePoint that’s fully modern, supported, and ready for whatever comes next!