What’s new for the Microsoft 365 developer at Build 2021

Office Add-ins team

It’s opening day at Microsoft Build 2021! The Microsoft 365 platform team is excited to be here (digitally) together with you again! The last 12-months have been challenging, as we shifted to the unchartered territory of remote work to the future of hybrid work. Throughout this disruption, Microsoft 365 developers have lead the charge by building collaborative apps built on top of the Microsoft 365 platform to keep workers connected and productive.  

Microsoft Graph is the fabric that connects your hybrid workplace 

Your organization’s Microsoft 365 data lives in Microsoft Graph. It’s the source for all the data and insights generated by the people creating and collaborating in productivity tools they use every day. Data from the Microsoft Graph API is an essential ingredient in the collaborative apps that shape the world of hybrid work. Let’s go through some of the exciting new features we’re announcing. 

Authentication and app security

In the world of hybrid work, app security and manageability are more important than ever. We’re introducing support for new authentication and B2C access patterns, including the ability to incorporate two-factor and multi-factor authentication into your solutions. We’re also excited to announce that Continuous Access Evaluation is now in preview. This enables users to monitor resources for security issues and if necessary, revoke access tokens. 

Insights, and data at scale

Developers can use Microsoft Graph data to bring a lot of content and context into their application. That data, when examined at scale, is a great source for organizational insights. We’ve got more ways than ever to consume or create insights using Microsoft Graph data. The new extensibility features for Microsoft Viva Connections, now available in preview with SharePoint Framework 1.13, offer a great way to consume Graph-powered insights built by Microsoft. And if you’re interested in creating your own insights, Microsoft Graph Data Connect is now an Azure-metered service. This means that you’re only paying for exactly the data you need to consume in your solution. 

Connector-powered workflows & experiences

Microsoft Graph connectors offer developers the opportunity to bring data into Microsoft Graph. Once there, you can surface that data in some of the most highly used, powerful experiences in Microsoft 365, like Search and Advanced eDiscovery. We’re previewing a new Signals API that works with connectors to allow third-party content to surface in the Office Hub. And, we’ve made search results available in the Windows search box and the Teams desktop and mobile clients. 

Find out more about Microsoft Graph

These are the highlights. And there are dozens of endpoints on the Microsoft Graph. We’ve got a full run-down of all that’s new in Microsoft Graph from Education to Windows, so make sure to check out the Microsoft Graph @ Build blog.

Build powerful collaborative experiences with Fluid Framework

At Build 2020, we announced Fluid Framework – a new framework designed to help every developer build better collaborative applications. This year, we’re excited to announce some Azure and Microsoft 365 integration which you can see below and in our on-demand session at Build.

Azure Fluid Relay

We are thrilled to announce the Azure Fluid Relay service, which is available in private preview. The Azure Fluid Relay gives you all the power of Fluid, but in a convenient, fully managed service. You can expect low latency, real-time collaboration that scales to hundreds of users per session. As a developer, you’ll receive world class performance in a fully managed service with no upfront cost, global presence with regional resilience, and the comfort that Azure Fluid Relay meets data residency and compliance requirements. Join the Azure Fluid Relay service private preview today!

Screenshot of Azure Fluid Relay service sample - currently in private preview so subject to change.


Fluid Framework Library for Microsoft 365

We’re excited to announce the Fluid Framework Library for Microsoft 365, which is available in private preview. The library enables developers to easily build collaborative, Fluid-powered apps in Microsoft Teams. These apps use the Fluid service within SharePoint. So instead of deploying and maintaining your own service or managing an Azure service, you can use a Fluid service built into Microsoft 365 tenants. This lets you integrate with Single Sign-on (SSO), Microsoft Graph, and more. Join the Fluid Framework Library for Microsoft 365 private preview today!

Fluid Framework Library for Microsoft 365 consisting of Teams, Sharepoint, OneDrive, and Microsoft 365 Security

Private preview of Fluid components in Teams chat

Fluid components in Microsoft Teams chat is now available in private preview and will expand to more customers in the coming months. These are powered by the web, edited in real-time, and work across Teams and Office apps. Fluid components in Teams chat allow users to send a message with a table, action items, or a list that can be co-authored and edited by everyone in line, minimizing the need for long chat threads and meetings. They also can be copied and pasted across Teams chats, helping users become more efficient.

Building world-class web apps with Microsoft Edge

Microsoft 365 developers have built world class solutions on top of the Microsoft Edge platform. We’re excited to share the latest updates on Microsoft Edge with you at Build 2021 and have captured some of the major news and announcements:

WebView2 now generally available

Since last Build, WebView2 has moved from preview to generally availability and production-ready across Win32 C/C++, WPF/WinForms, and WinUI 3. With WebView2, developers can take the Microsoft Edge web platform and embed it in native applications. No longer do developers need to choose between the web and native—they’re both first class citizens using WebView2 on Windows. Watch the What’s new in Microsoft Edge developer tools video for more details!

Integrate your business solutions with Microsoft Office Add-ins

Throughout the last 12 months, workers relied on productivity solutions built on top of Office to help them stay engaged and focused on work. Developers built solutions as Office Add-ins and we’re excited to share several of the new features and announcements on these at Microsoft Build.

Keyboard Shortcuts APIs now available

Developers are now able to configure custom keyboard shortcuts for Office Add-ins in Excel that can invoke any add-in related functionality. The possibilities are endless and keyboard shortcuts can be effective no matter the scenario of your add-in. Learn more about these APIs today.

Contextual Ribbon Tab APIs now available

A contextual tab is a hidden tab control in the Office ribbon that is displayed in the tab row when a specified event occurs in the Office document. You can now include custom contextual tabs in your Office Add-in and specify when they are visible or hidden, by creating event handlers that change the visibility. Learn more about this API today.

Excel 1.13 APIs requirement rolling out to production

We have over 2000 different APIs for you to explore and shape your data. These APIs help you get your data into the hands of users quickly and easily. Watch our on-demand session at Build to see an in-depth overview of these APIs.

Event-based Add-ins for Outlook rolling out to production featuring the onCompose Event

Announced back at Ignite 2020 in preview, we’re excited to share that Event-based Add-ins are now rolling out to production. This new extension point enables developers to integrate their solutions into Outlook while the user interacts with it. On this first release, you can launch add-ins automatically when composing e-mails or appointments.  Watch our on-demand session at Build to see an in-depth overview and check out or documentation.

Mailbox 1.10 APIs focused on Signature Scenario now generally available.

We’re also excited to share that requirement set Mailbox 1.10 is now generally available. This is suited if you’re building an admin-managed signature item – and comprises of 5 APIs: setSginatureAsync; getComposeTypeAsync; isClientSginatureEnabledAsync; disableClientSignatureAsync; and clickableInfobar. Watch our on-demand session at Build to see an in-depth overview of each of these APIs and try these out today.

New Events in preview

As part of the Event-based add-in feature, we are bringing additional events now available in preview (install beta build 16.0.14026.20000) which you can try on Outlook Web and Windows. These include the following events:

  • Recipients change
  • Attachments change
  • Appointment time change
  • Appointment recurrence change
  • Info bar dismiss

Watch our on-demand session at Build to see an in-depth overview of each of these events and try these out today and keep adding seamless experiences on your user’s Outlook experience.

Mailbox 1.8 is now supported in the new Outlook for Mac

With this, add-ion support in the new Outlook for Mac comes to parity with the classic Mac Outlook, so that now all Mac users can now use these flows. 1.8 includes the OnSend events as well as supporting the delegates scenario.  Mailbox 1.8 enables additional features and can assist the migration of Code injection plugins to Web add-ins. As a reminder, code Injection will be deprecated going forward

COM/VSTO and Web Add-ins Compatibility available today

COM/VSTO add-in compatibility means your Windows investment can coexist with your add-ins on Outlook Mac and OWA. Starting with build 16.0.13801.2XXX, you’ll find that we have a tool to suppress a web add-in only on the Windows platform and replace with a COM add-in. Learn more about this today.

Build with the SharePoint Framework to easily build your Microsoft 365 solutions

Developers building apps using the SharePoint Framework (SPFx) are utilizing the easiest way to build enterprise solutions for Microsoft 365. Here are some of the exciting new SharePoint Framework features and announcements we’re sharing with you at Build.

Viva Connections extensibility in private preview

Viva Connections is your gateway to a modern employee experience where you can build and integrate apps that shape culture and foster connections to help employees thrive. With SPFx, you have multiple ways to extend – using the same out-of-the-box or custom SPFx web parts, SPFx extensions (e.g., header, footer), and specific components for optimized mobile experiences. Sign up for private preview today and learn more about Viva Connections by watching our session.

Viva Connections extensibility preview showing Sharepoint Framework out of the box and custom components in action.

Enhanced Microsoft Teams Toolkit with native SPFx integration support, available in preview

The enhanced Teams Toolkit for Visual Studio and Visual Studio Code has native SPFx integration support which provides developers the option to choose the solution to be hosted in SharePoint. Get started with the Teams Toolkit today.

Microsoft Teams Toolkit showing what it looks like to start a developer project.

SharePoint Framework v1.12.1 now available

The latest version of SPFx (v1.12.1) released in April, provides developers with many updates such as Nodev14 and Gulp 4 support, additional support for complex Microsoft Teams solutions, ability to create Teams meetings apps via SPFx, more access to the page structure and context to avoid DOM dependency, support for Teams SDK v1.8, the general availability of list and library subscriptions,.

Design beautiful and engaging apps with the Fluent UI Design System

The Fluent UI Design System is a collection of UX frameworks for creating beautiful, cross-platform apps that share code, design, and interaction behavior. We’re excited to share the latest updates to Fluent UI here at Build this week!

Updated Microsoft Teams UI Kit available


The Fluent UI powered Microsoft Teams UI Kit allows developers to build powerful Teams-integrated applications. It offers a variety of design guidance via Figma files as well as high value controls like lists, swim lanes, and layout controls, as well as powerful data visualization controls. We’re happy to announce a new version of the Microsoft Teams UI Kit. The latest version makes it easier to design high-quality Teams apps with these new and updated features.

  • Mobile screens (responsive patterns) for all app capabilities and UI templates
  • App structure overview that describes the surfaces in Teams you can customize
  • New UI templates, including filter and settings, and more comprehensive guidelines
  • Much more

All controls are available via open source on GitHub.

Fluent UI vNext Alpha available for feedback

With an already rich React Library and recent v8 release, we’re already prepping our next release. We’d like to share with you the direction we’re taking the library with this alpha preview, which includes updates such as: Fluent-styled components that are easily customizable for your brand/theme; better optimization for render performance; refactored and slimmed down components; WCAG 2.1 compliance, and the ability to stay current with design updates via Design Tokens. Check out our early alpha today and provide early feedback to help us improve.

Fluent UI Alpha examples


Fluent UI web components available

Fluent UI Web Components provide you with Fluent-styled components with no JavaScript framework required. They offer the ability to use web platform for a smaller download size and high-performance solution for modern browsers, WCAG 2.1 AA compliance, and a flexible design system architecture. This also leverages Fluent design tokens which enables real-time design customization. Get started with Fluent UI Web Components today.

samples of fluid web UI components including radio buttons, check boxes, menus, and a example of a shopping app in Edge.

Fluent UI Android updates

New updates to Fluent UI Android include:

  • New controls: FacePile, FaceStack, ContextualCommanndBar, DrawerController, PersistentBottomSheet, and more!
  • Surface Duo-optimized controls, automatically avoiding the hinge when needed.
  • Accessibility improvements across all controls for TalkBack and bluetooth keyboard support.

Learn more about these updates today.

Fluent UI Apple updates

New updates to Fluent UI Apple include:

  • New iOS controls: SideTabBar, FaceStack, FacePile, ShimmerView, Cards, DrawerController, CommandBar, and more!
  • Improvements to iPad controls, like Notifications and Toasts no longer taking entire width of screen New macOS controls: Button, Link, Separator
  • Cocoapod consumption allows for importing just the controls you need

Learn more about these updates today.

Building apps that support dual-screen experiences on Surface Duo

The dual-screen Surface Duo has double the screen for double the productivity. To help Microsoft 365 app developers take advantage of this unique user experience, we’re sharing guidance for a variety of platforms, including web developers, .NET developers using Visual Studio and Xamarin, and Kotlin/Java developers. Check out our on-demand sessions at Microsoft Build, and visit the Surface Duo developer docs to learn more.

Creating modern Windows apps to support remote and hybrid work

Now, with the shift to remote work due to the pandemic and the beginning of hybrid work, the PC has never been more essential. With over 1.3 billion devices running Windows 10, modern apps have become critical to enable users to stay productive. From updates to Project Reunion to new GUI app support on WSL, learn more about the exciting new features we’ve built to support Windows developers.

Build the next generation of collaborative apps on Microsoft Teams

Microsoft Teams was built with the very purpose of enabling collaboration. And with over 145 million people using Teams every day, Teams has become the digital platform for work and learning. With hybrid workplace here, a new class of apps that we call collaborative apps, are essential to support this new way of work. So, we’re excited to share the new features and tools on our platform that developers can use to build these apps. Learn more about our new features in our blog in Tech Community.

In conclusion, we hope that you’ve enjoyed learning about what’s new with Microsoft 365. And, that you’re ready to sharpen your skills and deepen your knowledge. Please join us for our online sessions and make the most of Build, and don’t forget to sign up for the Microsoft 365 Developer Program if you haven’t yet already.  As ever, happy coding!

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