VSTO web add-ins vs Office 365 add-ins: Key differences to know

Purpose of Office 365 Add-ins development

The main purpose of Office 365 Add-ins development is to simplify work demands and speed up business data operations, whether in Excel, Outlook, Word, or PowerPoint.

These bespoke Office 365 Add-ins allow users to personalize their Office experience and optimize their workflows by interacting with external services and automating repetitive tasks.

Some examples of MS Office 365 Add-ins include:

• DocuSign:

  It is a fantastic tool that allows users to sign and send documents for signature directly from a Word or Outlook.

• Grammarly:

  This tool is a grammar and spelling checker integrated with Outlook or Word to provide real-time suggestions and corrections.

• Trello:

  A tremendous project management tool that can be integrated with Outlook to manage tasks and track progress.

Microsoft Office Market share

Planning to hire a top-rated VSTO Add-in development company?

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All in all, custom Office 365 Add-ins development is a recommended way that offers users with personalized Office experience and streamlined workflows with integrated external services.

Difference between VSTO web add-ins and Office 365 add-ins

While both of these development models serve the same goal, they differ in various aspects, including the platform they are built on, their functionalities, and their architecture.

#1 Platform Reliability

The VSTO web add-ins are built on the .NET framework, which is a popular platform for Windows desktop application development.Visual Studio is used by developers to produce VSTO add-ins, which are then deployed as COM add-ins. These add-ins are compatible with Microsoft Office 2010 and subsequent versions of the suite, and they interface with Office applications via a runtime library.

Office 365 add-ins, on the other hand, are written with web technologies like HTML, CSS, and JavaScript and hosted on web servers. These add-ins are compatible with Office 2013 and subsequent editions, as well as Office Online and Office for Mac. Add-ins for Office 365 may be built with any text editor or integrated development environment (IDE) that supports custom software development, such as Visual Studio Code, Sublime Text, or Atom.

#2 Add-in architecture

VSTO web add-ins are .NET assemblies that operate within the Office application process. This means they are strongly connected with the Office program and can directly use its object model. VSTO add-ins may be written in any .NET language, including C#, Visual Basic.NET, and F#.

Office 365 add-ins, on the other hand, are designed as browser-based online apps. The JavaScript API for Office, which provides a collection of JavaScript libraries for dealing with Office documents and objects, is used by these add-ins to interface with the Office program. Any web development framework, including Angular, React, and Vue, may be used to create Office 365 add-ins.

Read More: How to use Angular for Office 365 Add-in development?

#3 Features and Capabilities

VSTO web add-ins can offer a wide range of functionality within the Office program, such as custom ribbon tabs and buttons, task panes, custom form regions, and custom document actions. VSTO add-ins may also use the Office object model to change document content, create new documents, and interact with other Office functionalities.

Office 365 add-ins, on the other hand, are designed as browser-based online apps. The JavaScript API for Office, which provides a collection of JavaScript libraries for dealing with Office documents and objects, is used by these add-ins to interface with the Office program. Any web development framework, including Angular, React, and Vue, may be used to create Office 365 add-ins.

Here are some interesting facts about Microsoft Office platforms:

• Microsoft offers about 18 products, and according to statistics, 34% of its users are from the United States, with the United Kingdom coming in second with 8% of the overall customer base.
• Every hour in 2022, about 39, 930 individuals were using the Microsoft 365 platform.

Increase your business efficacy with Microsoft Power App Consulting Company

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#4 Compatibility and scalability

Office 365 add-ins, while not as tightly integrated with the Office application as VSTO add-ins, offer a number of advantages in terms of cross-platform compatibility and scalability. Since they are web-based, Office 365 add-ins may be used on a variety of devices and platforms, including Windows, macOS, iOS, and Android. Office 365 add-ins may also use cloud-based services like Microsoft Graph, which provides a consistent API for accessing data and functionality across numerous Microsoft services including OneDrive, SharePoint, and Teams.

#5 Complexity and expertise

Apart from these core differences, there are several other aspects to consider when deciding between VSTO web add-ins and Office 365 add-ins. The degree of programming experience necessary, the complexity of the add-in functionality, and the deployment and distribution procedure are all factors to consider. Because they are designed using the .NET framework and need knowledge of the COM and Office object models, VSTO add-ins often necessitate a higher degree of programming skill. Office 365 add-ins, on the other hand, may be created using more generally recognized and understood web development technologies.

Read More: How Microsoft Office 365 Add-Ins can supercharge your productivity?

#6 Integration and deployment

Another point to think about is the complexity of the add-in functionality. VSTO add-ins are better suitable for complicated, highly integrated add-ins that require deep interaction with the Office program. Office 365 add-ins, on the other hand, are better suited for lightweight, web-based add-ins that can be readily installed. So, ready to hire office Add-ins developers? Let's connect and discuss your needs.

VSTO web add-ins vs Office 365 add-ins: Key differences to know Microsoft Office is a suite of popular productivity applications, including Outlook, Word, Excel, and PowerPoint among others. With the advent of cloud computing, Microsoft has introduced two development models for creating add-ins that enhance the functionality of Office applications i.e., VSTO web add-ins and Office 365 add-ins. While both of these development models serve the same purpose, they differ in several key aspects, including their architecture, the platform they are built on, and their capabilities. In this blog, we will discuss the main differences between these two platforms. Let's start with the fundamentals before delving deeper into the subject. What is VSTO web Add-ins? VSTO (Visual Studio Tools for Office) web add-ins are a type of Office Add-in that is developed using the VSTO technology and is designed to run in the web version of Microsoft Office, such as Office Online or Outlook on the web. Traditionally, VSTO add-ins are developed using the .NET framework and are designed to run within the desktop version of Microsoft Office applications, such as Word, Excel, and PowerPoint. However, with the advent of Office 365 and web-based versions of Office applications, VSTO web add-ins have become increasingly popular. This prompted clients to hire ASP.NET MVC developers to meet their Add-in requirements. Looking for the best Excel Add-in development company? Contact us Purpose of VSTO Add-in development VSTO web add-ins are built using HTML, JavaScript, and CSS and are hosted on a web server. They can be used to extend the functionality of web-based Office applications in the same way that traditional VSTO add-ins extend the functionality of desktop Office applications. VSTO web add-ins can be used to add context menus, custom ribbons, and task panes to web-based Office applications. They may also be used to link with other web-based applications and APIs to give extra functionality to Office users. VSTO web add-ins are produced in Visual Studio and may be distributed to users via the Office Store or a corporate catalog. This is how VSTO web add-ins provide a powerful way to extend the features of web-based Office apps and provide a seamless user experience across web and desktop-based Office apps. What is Office 365 Add-in? Office 365 Add-ins are third-party applications that can be integrated into Microsoft Office applications such as Word, PowerPoint, Outlook, and Excel. These add-ins extend Office application capabilities by adding new features or services, automating repetitive tasks, or integrating with external services. Office 365 Add-ins can be developed using a variety of coding languages and technologies, like HTML, CSS, JavaScript, .NET, and more. They are hosted either on the developer's own web server or on a cloud-based platform such as Azure. Read More: Top 15 Add-ons for Outlook to enhance data privacy and security Purpose of Office 365 Add-ins development The main purpose of Office 365 Add-ins development is to simplify work demands and speed up business data operations, whether in Excel, Outlook, Word, or PowerPoint. These bespoke Office 365 Add-ins allow users to personalize their Office experience and optimize their workflows by interacting with external services and automating repetitive tasks. Some examples of MS Office 365 Add-ins include: DocuSign: It is a fantastic tool that allows users to sign and send documents for signature directly from a Word or Outlook. Grammarly: This tool is a grammar and spelling checker integrated with Outlook or Word to provide real-time suggestions and corrections. Trello: A tremendous project management tool that can be integrated with Outlook to manage tasks and track progress. Microsoft Office Market share Planning to hire a top-rated VSTO Add-in development company? Contact us now. All in all, custom Office 365 Add-ins development is a recommended way that offers users with personalized Office experience and streamlined workflows with integrated external services. Difference between VSTO web add-ins and Office 365 add-ins While both of these development models serve the same goal, they differ in various aspects, including the platform they are built on, their functionalities, and their architecture. #1 Platform Reliability The VSTO web add-ins are built on the .NET framework, which is a popular platform for Windows desktop application development.Visual Studio is used by developers to produce VSTO add-ins, which are then deployed as COM add-ins. These add-ins are compatible with Microsoft Office 2010 and subsequent versions of the suite, and they interface with Office applications via a runtime library. Office 365 add-ins, on the other hand, are written with web technologies like HTML, CSS, and JavaScript and hosted on web servers. These add-ins are compatible with Office 2013 and subsequent editions, as well as Office Online and Office for Mac. Add-ins for Office 365 may be built with any text editor or integrated development environment (IDE) that supports custom software development, such as Visual Studio Code, Sublime Text, or Atom. #2 Add-in architecture VSTO web add-ins are .NET assemblies that operate within the Office application process. This means they are strongly connected with the Office program and can directly use its object model. VSTO add-ins may be written in any .NET language, including C#, Visual Basic.NET, and F#. Office 365 add-ins, on the other hand, are designed as browser-based online apps. The JavaScript API for Office, which provides a collection of JavaScript libraries for dealing with Office documents and objects, is used by these add-ins to interface with the Office program. Any web development framework, including Angular, React, and Vue, may be used to create Office 365 add-ins. Read More: How to use Angular for Office 365 Add-in development? #3 Features and Capabilities VSTO web add-ins can offer a wide range of functionality within the Office program, such as custom ribbon tabs and buttons, task panes, custom form regions, and custom document actions. VSTO add-ins may also use the Office object model to change document content, create new documents, and interact with other Office functionalities. Office 365 add-ins, on the other hand, are designed as browser-based online apps. The JavaScript API for Office, which provides a collection of JavaScript libraries for dealing with Office documents and objects, is used by these add-ins to interface with the Office program. Any web development framework, including Angular, React, and Vue, may be used to create Office 365 add-ins. Here are some interesting facts about Microsoft Office platforms: Microsoft offers about 18 products, and according to statistics, 34% of its users are from the United States, with the United Kingdom coming in second with 8% of the overall customer base. Every hour in 2022, about 39, 930 individuals were using the Microsoft 365 platform. Increase your business efficacy with Microsoft Power App Consulting Company Contact us #4 Compatibility and scalability Office 365 add-ins, while not as tightly integrated with the Office application as VSTO add-ins, offer a number of advantages in terms of cross-platform compatibility and scalability. Since they are web-based, Office 365 add-ins may be used on a variety of devices and platforms, including Windows, macOS, iOS, and Android. Office 365 add-ins may also use cloud-based services like Microsoft Graph, which provides a consistent API for accessing data and functionality across numerous Microsoft services including OneDrive, SharePoint, and Teams. #5 Complexity and expertise Apart from these core differences, there are several other aspects to consider when deciding between VSTO web add-ins and Office 365 add-ins. The degree of programming experience necessary, the complexity of the add-in functionality, and the deployment and distribution procedure are all factors to consider. Because they are designed using the .NET framework and need knowledge of the COM and Office object models, VSTO add-ins often necessitate a higher degree of programming skill. Office 365 add-ins, on the other hand, may be created using more generally recognized and understood web development technologies. Read More: How Microsoft Office 365 Add-Ins can supercharge your productivity? #6 Integration and deployment Another point to think about is the complexity of the add-in functionality. VSTO add-ins are better suitable for complicated, highly integrated add-ins that require deep interaction with the Office program. Office 365 add-ins, on the other hand, are better suited for lightweight, web-based add-ins that can be readily installed. So, ready to hire office Add-ins developers? Let's connect and discuss your needs. How to Add Office.js Into an Existing VSTO Project If you already have a VSTO project and want to add modern web-based features, you do not always need to rebuild the entire add-in. You can add Office.js to support web-based Office features while keeping your existing VSTO functionality. However, VSTO and Office.js work differently. VSTO uses .NET and runs mainly with desktop Office applications, while Office.js uses JavaScript to build web-based Office Add-ins. So, adding Office.js usually means creating a separate web component and connecting it with your existing VSTO solution. Therefore, you must follow the steps below to add Office js to your existing VSTO project: Steps to Add Office.js to a VSTO Project 1. Review your existing VSTO project First, check what your VSTO add-in currently does. Identify the features, Office APIs, business logic, and services it uses. Then decide which features should remain in VSTO and which ones can be handled with Office.js. 2. Create the Office Add-in component Create a web-based Office Add-in using HTML, CSS, and JavaScript or TypeScript. Add the Office.js library and set up the required manifest and Office application. 3. Add Office.js features Use Office.js APIs to work with supported Office features. For example, you can use JavaScript to read or update data in an Excel workbook or work with supported Word or PowerPoint features. 4. Connect it with the VSTO solution If the new Office.js component needs to work with your existing VSTO application or backend services, create a clear connection between them. Keep important business logic and sensitive information on the server instead of exposing it in the browser. 5. Test the add-in Test the solution on the Office applications and platforms your users need. Office.js API support can differ based on the Office application, platform, and API version. Check these requirements before releasing the add-in. Things to Consider Before Adding Office.js Adding Office.js can be a useful step toward Building Custom Office Add-ins with Office.js, but it may not be suitable for every VSTO project. If your add-in depends heavily on VSTO features that are not available through Office.js, you may need a gradual migration instead of replacing everything at once. If you want to support Office on the web, Mac, or the new Outlook, consider moving suitable features from VSTO to an Office Add-in. This can make your solution easier to support across different platforms. Keep in mind: Office.js cannot replace every VSTO feature. Before making changes, compare the features and APIs used by your existing project with the Office.js APIs available for your target Office applications. Conclusion To summarize, there are significant differences between VSTO add-ins and Office Add-ins that developers should understand before choosing the right option for their projects. VSTO add-ins are built using the .NET Framework and Visual Studio Tools for Office (VSTO), while Office Add-ins are built using web technologies such as HTML, CSS, and JavaScript. VSTO add-ins are designed to work with Microsoft Office desktop applications on Windows and have limited cross-platform support. On the other hand, Bespoke Office Add-in are designed to work across supported Office applications and platforms. Office Add-ins also offer flexible deployment options through Microsoft 365 and Microsoft Marketplace. If you have an existing VSTO project, you can add Office Add-in functionality using Office.js without rebuilding the entire solution. Building Custom Office Add-ins with Office.js helps add web-based features while keeping suitable VSTO functionality. However, check Office.js API support before integration or migration. In conclusion, VSTO add-ins are suitable for Windows-based Office solutions, while Office Add-ins are a better option for modern, cross-platform applications. The right choice depends on your project's features, target platforms, and future requirements.

Kapil Panchal

A passionate Technical writer and an SEO freak working as a Content Development Manager at iFour Technolab, USA. With extensive experience in IT, Services, and Product sectors, I relish writing about Azure Cloud, Data Analytics, AI, & Workflow Automation and love sharing exceptional insights on various platforms. I believe in constant learning and am passionate about being better every day.