This document discusses using Gutenberg to build custom applications. It begins with an overview of Gutenberg and introduces a Gutenberg Object Plugin that structures Gutenberg block data to be accessible via an API. The document then presents a case study of a company that built a headless e-commerce site using WordPress, Gutenberg, GraphQL, and React. It encourages trying out the Gutenberg Object Plugin and code on GitHub to explore using Gutenberg for custom applications.