Create MS Office add-in /plugin for Outlook,
Excel, Word in Visual Studio: VB.NET, C#, C++

Add-in Express™
for Microsoft® Office and .net


  • Visual Studio 2012 - 2022
  • Visual Basic .NET
  • Visual C#
  • Visual C++ .NET


  • Excel 2000 - 2021
  • Outlook 2000 - 2021
  • Word 2000 - 2021
  • PowerPoint 2000 - 2021
  • Access 2000 - 2021
  • Project 2000 - 2021
  • Publisher 2003 - 2021
  • Visio 2002 - 2021
  • OneNote 2010 - 2016
  • InfoPath 2007 - 2013
  • MapPoint 2002 - 2013
  • FrontPage 2000 - 2003

Add-in Express for Office and .NET is your all-in-one framework for developing commercial class Microsoft Office extensions such as Office COM Add-in, Outlook plugin, Excel XLL, UDF, RTD Server and smart tag.

It works with all editions of Visual Studio, including Express, and all versions of Microsoft Office from 2000 to Office 2021/365.

Create world-class Office extensions

Add-in Express provides you with a range of visual designers, components, Visual Studio item and project templates and deployment tools that make creating quality Microsoft Office extensions easy and fun.

You no longer need to worry about implementing extensibility COM interfaces or hand coding your Office add-in UI using XML. Add-in Express makes deploying your applications a one-click operation and removes the headache of manually creating deployment scenarios and working with the Windows registry. Hard to believe? Just read real stories from real developers.

Feature tour

Creating version-neutral Office extensions with Add-in Express

One project for all Office versions and applications

Add-in Express has an optimized version-neutral core that is written in C# and is based on the .NET framework, COM interoperability and low-level Windows API. This makes it easy for you to create one Visual Studio project that supports all versions (2000 through 2021) and editions (Student, Home, Professional etc.) of Microsoft Office and target multiple applications in the Microsoft Office suite (Outlook, Word, Excel, PowerPoint and other apps.)

100% compatibility from version to version

You are not limited in your choice of Visual Studio versions (2012- 2022) or editions (Professional, Premium, Ultimate etc.) when developing with Add-in Express.

We have always complied with the simple rule that a project built on a prior version of Add-in Express must be 100% compatible with the next version of Add-in Express. This means that after installing the latest version of Add-in Express, you simply open your project and rebuild it� That's it!

Over 10,000 developers trust Add-in Express

Over 10 000 developers around the world already trust Add-in Express to help them create world-class Microsoft Office extensions. When you choose Add-in Express you can rely on our more than 10 years of experience in Microsoft Office development.

After all, Add-in Express was developed for our own add-ins and we still use it to this day for all our end-user solutions. We've invested a lot of time and resources in the development of Add-in Express and all our projects that are based on Add-in Express' tools, take far less time and effort than any of our competitors' products.

Over 40,000,000 PCs have Add-in Express run-time installed

Add-in Express based solutions have been tested, trusted and chosen by over 40 million users all over the world. From startups to international holdings, from student campuses to corporate networks... What about your own machine? :)

Support - the most important feature

There is nothing worse than buying a product and not getting timeous and accurate support. Rest assured that you will never find yourself in this situation with Add-in Express, see what our customers say:

Best of all is not that it is working flawlessly. The support level is outstanding! The answer is always friendly, straightforward and leads to a solution. Thomas Wetzel, Wisco

With Add-in Express I have absolutely no concerns that my query will be dealt with promptly, accurately and with great courtesy.
Richard Stevens, BOE Information Systems Ltd.

To have a better understanding of what kind of support you will actually get, read more customer stories.

Add-in Express for .net features and benefits

Microsoft Office extensibility

Add-in Express is completely based on the Office extensibility technology and extends it with unique features, which makes your Office development fast, easy and effective. You can develop all kinds of Office extensions including COM add-ins, smart tags, Excel RTD servers, Automation add-ins and XLLs. Learn more...


Add-in Express provides you with version-neutral run-time, so you needn't write code for each Office version. Your write your code once, and it runs on all versions, from 2000 to 2021/365. Moreover, your solutions are fully compatible with all Office editions, from Student and Home to Enterprise and Ultimate. Learn more...

Effective project architecture

Add-in Express generates ready-to-use solution templates that accumulated our long-term experience in Office development and deployment. The Add-in Express architecture makes your Office extensions secure, isolated, managed, deployable and updatable with your minimal efforts. Learn more...

Visual designers instead of coding

You use visual designers to customize Office menus, toolbars, ribbons, task panes, forms, windows, regions, option and property pages, etc. Add-in Express facilitates true Rapid Application Development (RAD), where you use components and visual designers instead of routine writing of glue code. Learn more...

Outlook is the premium platform

Outlook developers benefit from plenty of Outlook-related features. Using Add-in Express components and their visual designers you can create custom Outlook menus, toolbars and ribbons; make certain controls context sensitive, bind them to specified folders or content types, build option and folder property pages, add navigation pane shortcuts, embed view and form regions and more. Learn more...

1st-class GUI with Advanced Outlook Regions

Add-in Express gives you the Advanced Outlook Regions that are shared (you can place several forms from several add-ins into one region), version-neutral (your regions work equally well on Office 2003 - 2021), flexible (you can add regions for Outlook views, forms, To-Do bar, Navigation and Reading panes). Finally, you can create, close and move your regions at run-time. Learn more...

Any .NET controls on Office toolbars

On all versions of Outlook, Word, Excel and PowerPoint, you can add any built-in or third-party controls to Office toolbars. So, your own toolbars can host grids, tree views, list views, user controls, forms, etc. With Add-in Express you build a feature-rich GUI that your end-users will be fond of! Learn more...

Improved Excel extensions

If Excel is your target application, using Add-in Express you can create an amazing Excel addin GUI with the Advanced Office Task Panes that work for all Excel versions, effective real-time data servers with any number of RTD topics, new user-defined worksheet functions (UDFs) through Automation add-ins or Excel XLLs. Learn more...

Deployment made easy

With Add-in Express the deployment of your Office projects becomes so easy that you will forget about it. Each Add-in Express solution contains a setup project with all necessary prerequisites. Plus, your solutions fully support ClickOnce, so just build and publish your solution once, deploy and update anywhere. Learn more...

True RAD - you write applied code only

Add-in Express is entirely based on the Rapid Application Development (True RAD) paradigm and reduces the time you used to spend on COM add-in, smart tag and RTD server development at least by half. You write applied code only, Add-in Express does everything else. Learn more...