Create Office add-in in .NET

Develop plug-in for Outlook, Excel, Word in VB.NET, C#, C++

Add-in Express for Office and .NET is your all-in-one framework for developing commercial class extensions for all main applications and all versions of the Microsoft Office suite, from 2000 to Office 2016 and the newest Office 2019.

With an array of visual designers, components and Visual Studio project templates you can quickly create all sorts of Microsoft Office customizations including COM Add-ins, Outlook plug-ins, Excel XLLs, UDFs and RTD Servers, from a prototype to the final release.

Use visual designers to create slick UI of your Office add-in

Take your Office add-in development to another level

Add-in Express is a true RAD tool that empowers Office add-in developers with a number of unique features that no other tool offers.

Application-level Office extensibility

Visual Studio project templates for Office COM add-ins, XLL, RTD servers and smart tags

Use a set of Office-specific solution templates, wizards, visual designers and components to build various types of application-level extensions including:

  • Office COM Add-ins
  • Excel XLL
  • RTD servers
  • Automation add-ins
  • Smart tags

Version-independent plug-ins

Create an add-in for Office 2000-2013 with a single code base

The version-neutral core of Add-in Express gives Office developers the ability to:

  • Write a single code base to support all Office versions, from 2000 to 2019.
  • Develop version-independent add-ins with no application-specific solutions, no version-specific projects, no shared assemblies.
  • Selective version independence - all you need to do is specify the minimum version of Microsoft Office you want to support.

Visual designers instead of low-level coding

In-place visual designers to customize the Microsoft Office UI

Add-in Express provides a number of in-place visual designers to customize Office menus, toolbars, ribbons, task panes, forms, windows, regions, option and property pages, etc.

  • You use an array of components and visual designers to create any UI elements such as the Office Ribbon, Toolbars and Backstage View.
  • You can design your Office extension's UI without a single line of code to give your manager or customer the proof of concept in no time.
  • You don't need to worry about hand coding any plumbing code, focus on building your solution!

More about designers for Office ribbon, menus and toolbars.

Advanced view and form regions for Outlook 2000 - 2019

Three custom forms embedded into an Outlook Explorer window

Advanced View and Form Regions allow Outlook developers to embed custom .NET forms into Explorer and Inspector windows in all Outlook versions.

  • Advanced regions are shared, they may contain one or more forms created by one or several add-ins.
  • You can embed your regions into any Outlook form or view, add to the Navigation pane, Folder view pane, Reading pane or To-Do bar.
  • Your regions can be dragged between Outlook panes, hidden or minimized.
  • Your regions can be highlighted and bound to specified Outlook folders, content or context.

More about Advanced Outlook form and view regions.

Advanced task panes for Office 2000 - 2019

Advanced custom task pane in PowerPoint 2013

For your Excel, Word and PowerPoint add-ins, use Advanced Task Panes to extend document views with your own .NET forms:

  • Advanced task panes are version-neutral - they work on Excel, Word and PowerPoint 2019, 2016, 2013, 2010, 2007, 2003 and lower.
  • Your custom task panes can be shared, i.e. they may contain one and more forms created by one or several add-ins.
  • Custom Office task panes can be dragged between four docks or fixed in one of the docks.
  • Custom Office task panes can be hidden or minimized or highlighted.

More about Advanced Office task panes.

Easy deployment for Office add-ins

Feature-rich msi-based templates for your setup projects

Add-in Express allows you to get the maximum flexibility for you installations. Developers just need to choose the installation type and deployment model and Add-in Express automatically creates a setup project:

  • Windows Installer based setup projects
  • ClickOnce deployment
  • MSI-based web-deployment
  • InstallShield and WiX setup projects
  • Per-user and per-machine installations
  • Corporate deployment

More about Office add-in deployment.

Find more details

If you're developing Office add-ins, you're simply crazy to do so without Add-in Express

The product pays for itself during every coding session and is backed by a reliable and innovative vendor that cares deeply about its customers. Joe Zuffoletto, President, SmartCompany

We have been incredibly impressed by your products here at FedEx Technology Services!

I have to admit I do LOVE your products! We have used the Add-in Express for Office and .NET for two separate projects. Micah Bell, Customer Technology Advisor, FedEx Services

Add-in Express reduced our development time to a fraction of what it might have been

Originally, we had considered starting from scratch, but it did not take long for us to realize the benefit of going with Add-in Express. The results have been all we had hoped for, plus much more. Fabian Roken, Founder, Arbeitsblatt Profi

Leveraging Add-in Express saved me thousands of dollars

I am software developer with freelance business. Your tool was door to REAL rapid software development for me! When you're paid not by hours but on a project basis, it is very essential to cut any costs. Stan Chevski, Freelance software developer

I recommend that anyone developing COM add-ins stop wasting time and use Add-in Express

It is rare that a piece of software exceeds one's expectations, but Add-in Express has exceeded mine. The program worked exactly as described and made the development process a snap. Jeff Richmond, CTO, Computer Solutions Engineering

If you're not tired of hearing this yet, this is one of the best APIs I have used

This toolkit exceeded my expectation, even after watching your videos and seeing how the add-ins were created, and I had a working add-in with all the features I had hoped to add within 24-48 hours! Patrick Kelly, Senior Software Developer, USFamily.Net

With Add-in Express I was able to focus on the core functionality of my application

built a previous add-in from scratch and ended up spending a ton of time getting the basic COM add-in functions working correctly. With Add-in Express this was automatic and I was able to focus on the core functionality of my application. Jack Bretcher, President, Sonoma Enterprises, LLC

Supported IDEs:

  • Visual Studio 2019
  • Visual Studio 2017
  • Visual Studio 2015
  • Visual Studio 2013
  • Visual Studio 2012
  • Visual Studio 2010

Supported languages:

  • Visual Basic (VB.NET)
  • C#
  • C++.NET

Supported applications:

  • Excel 2000 - 2019
  • Outlook 2000 - 2019
  • Word 2000 - 2019
  • PowerPoint 2000 - 2019
  • Access 2000 - 2019
  • Project 2000 - 2019
  • Publisher 2003 - 2019
  • Visio 2002 - 2019
  • OneNote 2010 - 2016
  • InfoPath 2007 - 2013
  • FrontPage 2000 - 2003
  • MapPoint 2002 - 2013

How to buy this product

Add-in Express Ltd.

Add-in Express for Office and .net as well as all other development components available on are products of Add-in Express Ltd.

To purchase the product, please click the order link below. This will take you to Add-in Express's order page where you can review the subscriptions and prices and choose the one that is right for you:

Buy Add-in Express for Office and .net

Microsoft Visual Studio Industry Partner

Visual Studio Industry Partner

Add-in Express Ltd. is a privately held software development company located in Homel, Belarus. Established in 1998, Add-in Express Ltd. focuses on tools and solutions purposed for Microsoft Office integration. It has been a Microsoft Visual Studio Industry Partner for the last few years.

Contact us

Our working hours: 0am to 10am PST; 3am to 1pm EST; 8am to 6pm CET.

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