The Google Workspace Marketplace is Google's catalog of apps that extend Google Workspace, the suite that includes Gmail, Drive, Calendar, Docs, Sheets, Slides, Forms, Chat and Meet. It lists Google Workspace add-ons, Editor add-ons (for example a Sheets add-on, used from inside Sheets), Drive apps, web apps and Classroom add-ons, from security and CRM tools to document and project management.
A developer builds an app that extends at least one Workspace application, creates a Google Cloud project, configures OAuth (the protocol through which users grant the app access to their Google data), enables the Marketplace SDK and writes a store listing with text and graphics. A private app is available at once inside the developer's own organization. A public app can be installed by anyone, after a review by the Marketplace team. Users find apps by category, by the Google app they work with, by rating and by price, installation settings decide whether all users or only administrators can install an app, and organizations can restrict apps with allowlists.
Google charges no listing fee, and each app can be free or paid.