Excel, Word and PowerPoint web add-ins can now connect to COM add-ins

Last month Microsoft announced COM:Web Add-in Bridge, a new technology which lets Office web add-ins seamlessly connect to COM add-ins. The announcement was made at the annual Build 2019 dev conference.

Keyur Patel, Sr. Program Manager at Microsoft says: “This technology allows the web add-in to suppress itself, when an equivalent COM add-in exists. You can choose any equivalent COM add-in and check if it’s installed. If it’s found on that client machine, the web add-in does not appear in the ribbon.”

Keyur has confirmed that COM:Web Add-in Bridge is a technology that only works on Windows, and that two kinds of traditional add-ins are supported: COM add-ins and XLL add-ins. XLL add-ins have traditionally been used for writing custom user-defined functions (UDFs).

The public availability of this technology is available on Office Insiders build 16.0.11629.20214 and higher. It works with Excel, Word and PowerPoint COM and web add-ins.

I had a quick look at the manifest specification for the web add-in, and it appears that the bridge could support all COM add-ins, regardless of the framework they were built with. This would presumably include Office add-ins built with VSTO, but also others like Add-in Express and more.

Information about making your Office web add-in compatible with your COM Add-in can be found here.

As always, remember that I’m here to help with development services. I love making great Office add-ins, no matter what technology or device!