Creating, testing, and publishing add-ons involves a number of discrete steps. This guide provides an overview of each of these steps.
To create an add-on, you must create an Apps Script project and write code that defines the add-on's appearence and behavior. Depending on the problems the add-on is attempting to solve, you may need to write code that interacts with one or more of the Apps Script services or else use various Apps Script features such as triggers. You can also write code that connects to non-Google services in order to send or retrieve data from those services.
When building your add-on, be sure to follow the Best practices.
Testing unpublished add-ons
In order to provide the best experience for your users, you must throughly test your add-on prior to publishing it. You can install and test unpublished add-ons you or your team have developed, provided you have access to the add-on's script project. When testing your add-on, make sure the add-on UI appearence and behavior is what you intended. Try to anticipate how users interact with your add-on and provide a solid user experience.
When your add-on is finished you can publish it to the G Suite Marketplace for others to find and use. You can publish publicly for everyone to find, or publish only to your domain. See Publication visibility for more details.
Publishing is a complex process that requires preparation. When you publish to the G Suite Marketplace, you must provide a number of text, image, and URL assets that the G Suite Marketplace uses to show your add-on to others. It's best to create these assets before starting the publication process so you avoid delays.
Publishing add-ons publicly also requires your add-on to undergo an add-on review. During the review a Google review team member examines your add-on to verify that it meet's Google's style, content, and design guidelines and provides a good user experience. All add-ons published publicly must pass the review process in order to appear the G Suite Marketplace.
Managing published add-ons
After an add-on is published, at times you may want to update its code or how it appears in the G Suite Marketplace. You may also want to unpublish an add-on if it is no longer useful.