The Office Add-ins team’s mission is to empower developers with new capabilities and smoother experiences across Word, Excel, PowerPoint, and Outlook. At Ignite 2024, we announced agents for Microsoft 365 designed to help scale individual impact and transform of business processes. Continuing that journey, this year we’re deeply integrating Copilot agents into Office with add-in actions, building across the Microsoft 365 ecosystem with tooling and unified manifest improvements. We continue to deliver new capabilities across the Office Add-in platform. There’s a lot to announce, so let’s dive in!

Copilot agents become more powerful in Office with add-in actions

As part of the expanding capabilities for agents across Microsoft 365, you can now enhance your Copilot agent and extend your add-in to give it a natural language interface. Add-in actions give your agent new skills through the broad set of APIs available in office.js as part of a new add-in or from an existing one. Agents and add-ins bundled together with the unified manifest enable canvas integrations and scenarios for agents that until now required user interaction through an add-in itself. Add-in actions let users utilize agents to work with them through an agent, all through Copilot chat in Office.

You can use a chat interface and natural language via an agent to help your user:

• Complete tasks that have a complex or ambiguous starting point. The agent can provide initial information and help guide the user.
• Analyze and update content. The agent can analyze the content and update it depending on context.
• Insert data from a trusted data source directly.

You can now accomplish deep Office integration beyond the broader agent platform capabilities available. To learn more about these example scenarios, see Combine Copilot Agents with Office Add-ins.

As an example, here is a proof of concept from LexisNexis^® showcasing how an agent with specialized legal skills can collaborate with users directly on the Word canvas by working with their Lexis^® Create+ legal drafting extension.

Starting with declarative agents in Word, Excel, and PowerPoint, you can now create deep Office integrations with agents in Copilot. To learn more about these example scenarios and build an add-in action for your agent, see the overview documentation on Combine Copilot Agents with Office Add-ins.

Office Add-in platform and developer tooling updates

In addition to Add-in Actions, we’re introducing a range of updates across platform capabilities, APIs, developer tools, and add-in distribution options—making it simpler to build new or iterate on JavaScript add-ins.

Create an Office Add-in with unified manifest for Word, Excel, and PowerPoint (preview)

We’ve aligned add-ins in Word, Excel, and PowerPoint to use the same unified manifest and app model already adopted by Teams and Outlook. This unified approach allows developers to build a single app that runs consistently across Microsoft 365, simplifying deployment and reducing maintenance overhead.

Build your app using the Microsoft 365 Agents Toolkit (formerly Teams Toolkit)

To help you build using the unified manifest, we’ve updated our developer tools to make the experience straightforward. With the updated Microsoft 365 Agents Toolkit, you can build a single solution that works seamlessly across Word, Excel, PowerPoint, Outlook, Teams, and Microsoft 365. Create a new app with the unified manifest or convert your existing Office Add-ins that use the add-in only manifest, and debug in targeted Office app.

In addition, you can test the app with unified manifest by deploying it in your tenant in the Integrated apps page under Microsoft Admin Center > Settings, which allows admins to manage app access at both the app and user (group) levels. For more information, see Introducing the Microsoft 365 Agents Toolkit.

Office Add-in coding assistance in GitHub Copilot extension (preview)

To enable a smoother and more efficient integration development process, we’re working to provide robust development tools to help partners quickly onboard, transition, and expand their solutions. We’re introducing the preview of the Office Add-in coding assistant in the GitHub Copilot extension for Microsoft 365 Agent Toolkit (@m365agents).

This new capability enables developers to generate office.js code for Word, Excel, and PowerPoint add-ins using natural-language prompts—making it faster and easier to build and extend Microsoft 365 experiences.

• Instant scaffolding – Create complete add-in projects with a single prompt, including manifest, HTML, and TypeScript boilerplate.
• Context-aware suggestions – Generate better code. The extension understands the Office JS object model, your open files, and best practice patterns.
• Built-in snippets – Insert Office JavaScript API code snippets without looking through documents.
• Real-time explanations – Accelerate your learning and keep up to date.

For more information, see GitHub Copilot extension for Microsoft 365 Agents Toolkit on GitHub.

Event-based activation for Excel, PowerPoint, and Word add-ins

Available in May 2025 for Windows and web, add-ins for your organization can launch automatically in the background whenever a document is created or opened. This allows the add-in to validate, insert, or refresh critical content without any extra user steps.

• For developers, modify the manifest to specify whether the add-in is launched at document creation or open stage.
• For Microsoft 365 admins, deploy the add-in through admin center: The feature only works for centrally deployed add-ins. Admins can either find the add-in from the admin portal or upload the add-in, and then deploy it to the selected users, groups, or entire organization.
• For add-in users, the add-ins automatically run in the background, providing a non-intrusive experience.

Other ways to leverage the event-based add-in activation feature:

• Enhanced security: Enforce data protection policies automatically to protect sensitive information without relying on user actions. This ensures consistent and robust data protection across all documents.
• Improved compliance: By automating compliance checks, organizations can ensure that all documents adhere to regulatory requirements, reducing the risk of data breaches and non-compliance penalties.
• Consistent style and formatting: Validating style and formatting when a document opens ensures every user adheres to the organization’s latest standards.

Many partners are already incorporating this new capability into their add-ins. For example, the following video from Fortra illustrates how it leverages event-based add-in activation feature for their data loss protection add-in.

Word API and add-in updates

We continue moving forward in our commitment to innovation and excellence in document management solutions. Our focus is on creating structured and formatted documents and facilitating the review of changes between collaborators.

The following features are supported for Windows, Mac, and iPad with WordApiDesktop 1.2 requirement set:

• Create more dynamic content with precise control over the placement of Shapes, TextBox, and Canvas images. Place a text stamp at an exact location in the header or footer of an agreement document, insert branded visual elements such as company logo or certification seals at fixed position across all pages, or add confidentiality labels to specific regions of a document.
• Easily navigate documents with Page and Window support. Detect the pages that the user is viewing and editing or navigate to a specific page. For example, your add-in can annotate only the visible text that the user is currently viewing, rather than applying annotations across the entire document.
• Compare two documents in Base64. The compare feature is widely used in document co-authoring and review processes. compareFromBase64 format support enables comparison based on the consistent format of document content transferred across different systems and platforms.

Additionally, we’ve accelerated our speed of delivery APIs for Windows and Mac. Developers can expect a faster rollout of preview APIs that enable them to:

• Create more cohesive documents from templates with Template and Language objects.
• Build structured documents with new types of Content Controls.
• Improve document review support with viewing document history and protecting the document content.
• Protect the document by managing sensitivity labels.

For more information on the new Word JavaScript requirement sets, see the overview page.

Citation add-ins now on Reference tab in Word

To streamline add-in activation and support users as they complete their tasks, Word now allows end users to discover, acquire, and use popular third-party reference add-ins directly from the References tab. The most recently used add-in will be pinned to the ribbon, enabling quick access, and users can easily switch between citation managers using the dropdown menu.

Excel API and add-in updates

Earlier this year, we introduced ExcelApi 1.18 to add support for creating, deleting, and managing notes in a workbook. This requirement set also expands support for cell formatting with Excel.CheckboxCellControl and Excel.RangeTextRun to further customize the cells in spreadsheet. We continue to invest in Excel APIs and are releasing the new requirement sets ExcelApi 1.19 and CustomFunctionsRuntime 1.5 in May 2025.

Enhance data visualization with advanced data label and shape customization

To support richer, more flexible chart customization and shape manipulation in Excel, we’ve introduced new APIs that give developers greater control over chart data labels and shapes.

• Specify the geometric shape type of a data label with geometricShapeType.
• Set the location of a label by using existing label APIs and set the height and width of a label shape with setHeight(height: number) and setWidth(width: number). To place the callout support anchor in the location you desire, get the tail anchor via getTailAnchor(), and then set the left and top position with ChartDataLabelAnchor.
• Get the string or substring of a data label via getSubstring(start: number, length: number) and further format the string with the existing API class Excel.ChartFormatString.
• Customize and format the leaderLines of data labels in charts using the new classes ChartLeaderLines and ChartLeaderLinesFormat.
• With the new getActiveShape() method, get the current active shape in the workbook and then control and edit it with the existing Shape class.

New Excel data type APIs

In 2021 we introduced the first set of APIs that allowed developers use data type structures within their add-ins: Announcing Data Types APIs. We’re excited to announce that we are on the next stage of this journey. Check out the new set of capabilities that can help supercharge your add-ins.

• Custom providers for linked entities. Leverage the same capabilities found in Stocks and Geography data types. Register a provider, allow user-initiated refreshes, and defer properties that eliminate downloading all the data at once.
• Values with metadata. Quickly create basic values with additional data behind them. They look and act like numbers or text but can contain much more information you can easily access.
• Dot functions. Add custom functions to values with properties (such as entities).
• New card view layouts. We’ve introduced a 2-column layout which allows properties to be viewed side by side in the card.

Undo support for Excel add-ins (preview)

The new undo support feature changes how users interact with add-ins. It preserves add-in behavior in the Excel undo stack and allows users to undo add-in actions just like regular Excel actions, improving the integration of third-party solutions with Excel. Best of all, add-ins automatically have access to this preview feature—no additional settings are required.

Add-ins with complicated operations can combine several steps into one undo action, so we also provided the capability to customize the undo group allowing partners to tailor their ideal experience.

To see how to use this capability to streamline the product experience, watch the following example from our partner Velixo.

PowerPoint API updates

Since late 2024, we’ve brought new functionality to PowerPoint extensibility. PowerPointAPI 1.6 introduced the ability to get and set hyperlinks on a slide. PowerPointAPI 1.7 added DocumentProperties, CustomProperites, and CustomXMLPart to various elements in the presentation, including the shape, slide, slide layout, and slide master for custom XML parts. Now we are releasing PowerPointAPI 1.8 with the following added functionality.

• Create bindings or references to shapes like the equivalent functionality in Excel and Word.
• Create and replace tables programmatically and format strings within table cells with TextRun.
• Export a slide as a Base64 and get an image of a slide as a Base64 string.
• Set zOrder for your shapes in PowerPoint.
• Fill a shape with a Base64 image.
• Group and ungroup shapes.

We’re excited to see what you build with the functionality that these new APIs unlock for you in PowerPoint.

Outlook API updates

Every year, we focus on delivering features you need to enhance your Outlook add-ins and enable experiences not previously possible.

Explore the Mailbox 1.15 JavaScript API requirement set

The release of Mailbox requirement set 1.15 marks another milestone to support even more scenarios in new Outlook on Windows, such as spam reporting, data loss prevention (DLP), and attachment management. Mailbox 1.15 is generally available in Outlook on Windows (new and classic versions) and on the web, so you can use these features today.

• Enhance the reporting experience of your integrated spam-reporting add-in and provide better guidance to users on how to report suspicious messages. With radio button options and the “Don’t show this message again” checkbox option, you can further refine the information you need from your users.
• Customize the recommendations and alerts of your Smart Alerts add-in. Using the errorMessageMarkdown property, create ordered and unordered lists, emphasize important text, and include hyperlinks. Aside from opening task panes from the Smart Alerts dialog, you can now also run a function directly from the dialog and reduce the manual steps needed from a user to fix a message or comply with their organization’s policies.
• Programmatically send a mail item using the sendAsync method. For DLP solutions, the implementation of the sendAsync method in a Smart Alerts add-in streamlines a user’s experience especially when recommending changes to the mail items being sent.

These are just a few scenarios you can try. For more information, see the new Outlook Dev Center.

Microsoft 365 unified store and add-ins distribution improvements

Add-in distribution, discovery, and activation are essential stages in the lifecycle of an add-in product. To support developers in reaching their users more effectively, Microsoft offers a variety of channels and solutions such as admin central deployment, add-in installation widgets, modernized in-app store, and scenario-based entry points. We’re bringing the following new enhancements to make the add-in to reach your targeted customer easier.

Seamlessly install your web add-in with your main application on Windows

If you have a Windows application or a COM/VSTO add-in that works in conjunction with your Office Web Add-in, consider including the web add-in in the installation or upgrade package. This allows end users to seamlessly install the web add-in alongside your main application, with no additional steps required. This installation method is now generally available for Excel, PowerPoint, and Word add-ins.

For more information, see Include the add-in in the installation of a Windows app or COM/VSTO add-in.

Modernized store for Office Add-ins and Copilot agents

The Office Add-ins store serves as a centralized hub for users to discover, explore, install, and manage add-ins provided by Microsoft and partners. The updated store, integrated into Word, Excel, and PowerPoint, provides consistent experiences across all Microsoft 365 apps. It’s designed to be more modern, user-friendly, and easy to navigate. Users can discover, acquire and manage Copilot Agents in the new store. We’re gradually rolling out the new store to all Excel, PowerPoint, and Word enterprise users and it will be generally available for Microsoft 365 for Windows and web users soon.

More resources

We know we’ve presented a lot in this blog post, but we hope you’re as excited about these new features as we are. Take a moment to learn more and engage with us!

• Learn more by using our Office Add-ins and Script Lab developer documentation.
• Ask questions on Stack Overflow using the office-js or outlook-web-addins or on GitHub.
• Share your feedback on Office Add-ins at Microsoft 365 Developer Platform Ideas forum.
• Join us on our monthly community calls, the second Wednesday of each month at 8:00 AM Pacific Time.
• Join the Microsoft 365 developer program to get the access and resources you need to develop your Office Add-in.
• Discover resources for Office Add-ins on the Office Dev Center.

Happy coding!