Microsoft Office Add-ins (including ExtendSync and ExtendInsights) run as web applications.
However, Microsoft does not always use your default browser to render these add-ins.
Instead, the browser engine used depends on:
Your Windows or macOS version
Your Office / Microsoft 365 version
Whether you are using desktop Outlook or Outlook on the web
This article explains which browser your add-in uses, and how to clear that browser’s cache when troubleshooting.
Windows Users
The version used is dependent on the combination of your Operating System and Office Version.
(Support for Internet Explorer ended on June 15, 2022)
Windows Version | Office Version | Browser Engine Used |
Windows (any) + Office 2013 or later (non-subscription) | — | Internet Explorer 11 |
Windows 10 < Version 1903 + Microsoft 365 | — | Internet Explorer 11 |
Windows 10 ≥ Version 1903 + Microsoft 365 < Version 16.0.11629 | — | Internet Explorer 11 |
Windows 10 ≥ Version 1903 + Microsoft 365 ≥ Version 16.0.11629 | — | Microsoft Edge (WebView2) |
Office on the Web | Any OS | Browser in use (Edge, Chrome, Firefox, Safari, etc.) |
How to Clear the Browser Cache (Windows)
If Your Add-In Uses Microsoft Edge (WebView2)
Beginning with Office 365 version 16.0.11629 and Windows 10 version 1903, Office Add-ins running on Office 365 for Windows will use Microsoft Edge.
🔧 To clear Edge cache, close the CloudExtend application first and then follow the instructions here.
If Your Add-In Uses Internet Explorer 11
All lower versions of Windows and Office will use Internet Explorer (IE).
🔧 To clear IE cache, close the CloudExtend application first and then follow the instructions here.
Mac Users
Microsoft Office Add-ins on macOS use Safari.
Determine which browser is used
Outlook for Mac (desktop app) → Safari
Office on the Web → whichever browser you opened Outlook in
Clear Safari Cache
Open Safari.
Go to Safari > Preferences > Advanced.
Enable Show Develop menu in menu bar.
From the menu bar, click Develop > Empty Caches.
Restart Outlook.
➡️ See full instructions to clear Safari cache, here.
Clear Add-In Cache (Built-In Option)
If the add-in loads:
Click the ( i ) icon at the top-right of the add-in.
Select Clear Web Cache.
Need Help?
If you're not sure which browser your add-in is using or cache-clearing did not resolve your issue:
💬 Chat with us (bottom-right)
📧 Email cloudextend-support@celigo.com