How to make Internet Explorer add-on for IE7,
IE8, IE9 and IE11 in VB.NET, C#, C++

Add-in Express™
for Internet Explorer® and Microsoft® .net

Version-neutrality - your IE add-ons work for IE6 - IE11

Add-in Express delivers version-neutral interop assemblies based on the Internet Explorer 6.0 type library. Using these assemblies you can program version-neutral add-ons compatible with all Internet Explorer versions, i.e. from IE 6 through IE 11.

You can develop add-ons for a specific IE version, too. For example, if you want your plug-in to work with IE8, IE9, IE10 and IE11 - simply use the interop assembly for the IE 8 type library, and your add-in will load into that version and all subsequent IE versions. You can choose any interop assembly regardless of the actual IE version installed on your development PC.

Project Wizard to create add-ons for IE6 - IE11

Stop counting bits - your IE plug-ins are bit-insensitive

By default, all your solutions based on Add-in Express are compiled for the Any CPU platform. So all your IE plug-ins are bit-insensitive (or bit-neutral). However, to make your IE add-ons more secure and stable, Add-in Express isolates each of them in a separate application domain by using a special Win32 "shim", the Add-in Express Loader. There are two versions of the loader, one for the 32-bit and the other for 64-bit CPU. Both versions are included in IE add-on setup projects and are separately registered for 32- and 64-bit versions of Internet Explorer. A setup project created by Add-in Express will require only minor modifications: you can adjust simple properties such as SupportUrl, add required files, etc. All custom actions needed for add-on registration are generated automatically.

IE add-on project in the Solution window of Visual Studio