OpenAPI for Excel

Latest release: Version 1.3.8 (March 24, 2021)

Verify which version of Excel is running on your machine before downloading the add-in. See the Support page for more information.

Download (32-bit)

Download (64-bit)

For more information about this release, please see Add-in Release Notes.


Version 1 and up supports Windows only and requires the following software:

  • Microsoft Office 2010 or later (most recent versions recommended for optimal user experience).
  • .Net Framework Runtime 4.6.1 or later. See Microsoft's download page here. Under Run Apps → click Download .NET Framework Runtime.
    • Follow these steps to determine which version is installed on your machine.


The OpenAPI for Excel add-in behaves as any other add-in and can be installed in two ways, either for one-time use or as persistent installation.

One-time use

Using the add-in by opening the .xll-file with Excel ensures no changes are saved to Excel's add-in settings. This is useful for testing purposes or when you're looking to experiment with the add-in for the first time, such as in the Get Started in 5 Minutes or Less guide. This procedure does not affect functionality and removes any and all traces after Excel is closed. Make sure to load the add-in first if it is not installed persistently when opening Excel spreadsheets that use OpenAPI for Excel formulas. If the spreadsheets display numerous #NAME? errors, this is likely caused by a missing add-in, as Excel cannot find the formulas referenced in each of the affected cells.

Persistent installation

Loading the add-in automatically each time Excel is launched can be achieved by adding the .xll file to Excel's add-in list under settings:

  1. Save the .xll-file in a (permanent) location. The downloads folder is not recommended. If the file is removed, the add-in will fail to load and Excel will throw errors every time it is launched.
  2. Open Options in Excel and navigate to the Add-ins section.
  3. Click Go... at the bottom of the page to manage Excel add-ins.
  4. Click Browse and navigate to the location where the .xll-file is stored.
  5. Select the file and make sure the OpenAPI for Excel  Add-in is ticked in the Add-ins screen.
  6. If prompted, confirm to copy the add-in file to the Addins folder.
  7. Click OK. The OpenAPI tab now appears in Excel and is ready for use every time Excel is launched.

Updating to a newer version of the OpenAPI for Excel add-in requires removal of the old add-in from the settings menu before the newer version is added to prevent conflicts. Please make sure the default add-ins folder does not contain any OpenAPI for Excel add-ins before loading a newer version. The usual location of the add-in folder is: C:\Users\UserName\AppData\Roaming\Microsoft\AddIns. Also check whether any COM add-ins remain in the add-ins menu. These should be removed as well.