Runtimes element

Specifies the runtime of your add-in. Child of the Host element.


When running in Office on Windows, an add-in that has a <Runtimes> element in its manifest does not necessarily run in the same webview control as it otherwise would. For more information about how the versions of Windows and Office determine what webview control is normally used, see Browsers used by Office Add-ins. If the conditions described there for using Microsoft Edge with WebView2 (Chromium-based) are met, then the add-in uses that browser whether or not it has a <Runtimes> element. However, when those conditions are not met, an add-in with a <Runtimes> element always uses Internet Explorer 11 regardless of the Windows or Microsoft 365 version.

Add-in type: Task pane, Mail

Valid only in these VersionOverrides schemas:

  • Task pane 1.0
  • Mail 1.1

For more information, see Version overrides in the manifest.

Associated with these requirement sets:


For the shared JavaScript runtime, this element enables the ribbon, task pane, and other supported components to use the same runtime. However, the SharedRuntime requirement set is only available in some Office applications. For more information, see Shared runtime requirement sets.


Note that the event-based activation and integrated spam reporting features must use the same runtime. Multiple runtimes aren't currently supported in Outlook.


    <Runtime resid="ContosoAddin.Url" lifetime="long" />

Contained in


Child elements

Element Required Description
Runtime Yes The runtime for your add-in. Important: At present, you can only define one <Runtime> element.

See also