Sideload Office Add-ins in Office Online for testing

You can install an Office Add-in for testing without having to first put it in an add-in catalog by using sideloading. Sideloading can be done in either Office 365 or Office Online. The procedure is slightly different for the two platforms.

When you sideload an add-in, the add-in manifest is stored in the browser's local storage, so if you clear the browser's cache, or switch to a different browser, you have to sideload the add-in again.

Note

Sideloading as described in this article is supported on Word, Excel, and PowerPoint. To sideload an Outlook add-in, see Sideload Outlook add-ins for testing.

The following video walks you through the process of sideloading your add-in in Office desktop or Office Online.

Sideload an Office Add-in in Office 365

  1. Sign in to your Office 365 account.

  2. Open the App Launcher on the left end of the toolbar and select Excel, Word, or PowerPoint, and then create a new document.

  3. Open the Insert tab on the ribbon and, in the Add-ins section, choose Office Add-ins.

  4. On the Office Add-ins dialog, select the MY ORGANIZATION tab, and then Upload My Add-in.

    A dialog titled Office Add-in with a link near the upper left corner that says "Upload My Add-in"

  5. Browse to the add-in manifest file, and then select Upload.

    The upload add-in dialog with buttons for browse, upload, and cancel

  6. Verify that your add-in is installed. For example, if it is an add-in command, it should appear on either the ribbon or the context menu. If it is a task pane add-in the pane should appear.

Sideload an Office Add-in in Office Online

  1. Open Microsoft Office Online.

  2. In Get started with the online apps now, choose Excel, Word, or PowerPoint; and then open a new document.

  3. Open the Insert tab on the ribbon and, in the Add-ins section, choose Office Add-ins.

  4. On the Office Add-ins dialog, select the MY ADD-INS tab, choose Manage My Add-ins, and then Upload My Add-in.

    The Office Add-ins dialog with a drop-down in the upper right reading "Manage my add-ins" and a drop-down below it with the option "Upload My Add-in"

  5. Browse to the add-in manifest file, and then select Upload.

    The upload add-in dialog with buttons for browse, upload, and cancel.

  6. Verify that your add-in is installed. For example, if it is an add-in command, it should appear on either the ribbon or the context menu. If it is a task pane add-in, the pane should appear.

Note

To test your Office Add-in with Edge, enter “about:flags” in the Edge search bar to bring up the Developer Settings options. Check the “Allow localhost loopback” option and restart Edge.

The Edge Allow localhost loopback option with the box checked.

Sideload an add-in when using Visual Studio

If you're using Visual Studio to develop your add-in, the process to sideload is similar. The only difference is that you must update the value of the SourceURL element in your manifest to include the full URL where the add-in is deployed.

Note

Although you can sideload add-ins from Visual Studio to Office Online, you cannot debug them from Visual Studio. To debug you will need to use the browser debugging tools. For more information, see Debug add-ins in Office Online.

  1. In Visual Studio, show the Properties window by choosing View -> Properties Window.
  2. In the Solution Explorer, select the web project. This will display properties for the project in the Properties window.
  3. In the Properties window, copy the SSL URL.
  4. In the add-in project, open the manifest XML file. Be sure you are editing the source XML. For some project types Visual Studio will open a visual view of the XML which will not work for the next step.
  5. Search and replace all instances of ~remoteAppUrl/ with the SSL URL you just copied. You will see several replacements depending on the project type, and the new URLs will appear similar to https://localhost:44300/Home.html.
  6. Save the XML file.
  7. Right click the web project and choose Debug -> Start new instance. This will run the web project without launching Office.
  8. From Office Online, sideload the add-in using steps previously described in Sideload an Office Add-in in Office Online.