Build an Excel task pane add-in

In this article, you'll walk through the process of building an Excel task pane add-in.

Create the add-in

You can create an Office Add-in by using the Yeoman generator for Office Add-ins or Visual Studio. The Yeoman generator creates a Node.js project that can be managed with Visual Studio Code or any other editor, whereas Visual Studio creates a Visual Studio solution. Select the tab for the one you'd like to use and then follow the instructions to create your add-in and test it locally.


  • Node.js (the latest LTS version). Visit the Node.js site to download and install the right version for your operating system.

  • The latest version of Yeoman and the Yeoman generator for Office Add-ins. To install these tools globally, run the following command via the command prompt.

    npm install -g yo generator-office


    Even if you've previously installed the Yeoman generator, we recommend you update your package to the latest version from npm.

  • Office connected to a Microsoft 365 subscription (including Office on the web).


    If you don't already have Office, you might qualify for a Microsoft 365 E5 developer subscription through the Microsoft 365 Developer Program; for details, see the FAQ. Alternatively, you can sign up for a 1-month free trial or purchase a Microsoft 365 plan.

Create the add-in project

Run the following command to create an add-in project using the Yeoman generator. A folder that contains the project will be added to the current directory.

yo office


When you run the yo office command, you may receive prompts about the data collection policies of Yeoman and the Office Add-in CLI tools. Use the information that's provided to respond to the prompts as you see fit.

When prompted, provide the following information to create your add-in project.

  • Choose a project type: Office Add-in Task Pane project
  • Choose a script type: Javascript
  • What do you want to name your add-in? My Office Add-in
  • Which Office client application would you like to support? Excel

The Yeoman Generator for Office Add-ins command line interface.

After you complete the wizard, the generator creates the project and installs supporting Node components.


If you're using Node.js version 20.0.0 or later, you may see a warning when the generator runs the installation that you have an unsupported engine. We're working on a fix for this. In the meantime, the warning doesn't affect the generator or the project you generate, so it can be ignored.


You can ignore the next steps guidance that the Yeoman generator provides after the add-in project's been created. The step-by-step instructions within this article provide all of the guidance you'll need to complete this tutorial.

Explore the project

The add-in project that you've created with the Yeoman generator contains sample code for a basic task pane add-in. If you'd like to explore the components of your add-in project, open the project in your code editor and review the files listed below. When you're ready to try out your add-in, proceed to the next section.

  • The ./manifest.xml file in the root directory of the project defines the settings and capabilities of the add-in.
  • The ./src/taskpane/taskpane.html file contains the HTML markup for the task pane.
  • The ./src/taskpane/taskpane.css file contains the CSS that's applied to content in the task pane.
  • The ./src/taskpane/taskpane.js file contains the Office JavaScript API code that facilitates interaction between the task pane and the Office client application.

Try it out

  1. Navigate to the root folder of the project.

    cd "My Office Add-in"
  2. Complete the following steps to start the local web server and sideload your add-in.


    Office Add-ins should use HTTPS, not HTTP, even while you're developing. If you're prompted to install a certificate after you run one of the following commands, accept the prompt to install the certificate that the Yeoman generator provides. You may also have to run your command prompt or terminal as an administrator for the changes to be made.


    If you're testing your add-in on Mac, run the following command before proceeding. When you run this command, the local web server starts.

    npm run dev-server
    • To test your add-in in Excel, run the following command in the root directory of your project. This starts the local web server and opens Excel with your add-in loaded.

      npm start
    • To test your add-in in Excel on a browser, run the following command in the root directory of your project. When you run this command, the local web server starts. Replace "{url}" with the URL of an Excel document on your OneDrive or a SharePoint library to which you have permissions.


      If you are developing on a Mac, enclose the {url} in single quotation marks. Do not do this on Windows.

      npm run start:web -- --document {url}

      The following are examples.

      • npm run start:web -- --document
      • npm run start:web -- --document!jkcH7spkM4EGgcZUgqthk4IK3NOypVw?e=Z6G1qp
      • npm run start:web -- --document

      If your add-in doesn't sideload in the document, manually sideload it by following the instructions in Manually sideload add-ins to Office on the web.

  3. In Excel, choose the Home tab, and then choose the Show Taskpane button on the ribbon to open the add-in task pane.

    The Excel Home menu, with the Show Taskpane button highlighted.

  4. Select any range of cells in the worksheet.

  5. At the bottom of the task pane, choose the Run link to set the color of the selected range to yellow.

    The add-in task pane open in Excel, with the Run button highlighted in the add-in task pane.

Next steps

Congratulations, you've successfully created an Excel task pane add-in! Next, learn more about the capabilities of an Excel add-in and build a more complex add-in by following along with the Excel add-in tutorial.


Code samples

See also