Gatsby is an open source framework for building websites with React, first released in 2015. Its documentation describes it as “a React-based open source framework for creating websites,” and in its original and best-known form it works as a static site generator: it takes content and React components and pre-renders them into HTML, JavaScript, and assets at build time, producing a fast site that can be served from a content delivery network.
Gatsby became one of the flagship tools of the early JAMstack approach, a way of building sites from pre-built markup, reusable APIs, and JavaScript rather than a traditional server rendering pages on each request. By generating static files ahead of time, Gatsby sites could be deployed to simple static hosting while still being authored with the component model and developer experience of React.
A distinctive feature of Gatsby is its GraphQL data layer. Rather than fetching from many different sources at runtime, a Gatsby build pulls data from sources such as Markdown files, APIs, databases, and headless content management systems into a unified GraphQL store. Components then query exactly the data they need from that single graph, and the framework’s documentation highlights how this lets developers “pull data from your favorite headless CMS easily.”
Although the output is static, the delivered pages are still React applications. After the pre-rendered HTML loads, Gatsby hydrates it in the browser so the page becomes a fully interactive React single-page application, combining the fast initial load of static files with client-side interactivity.
The Gatsby source code is maintained at github.com/gatsbyjs/gatsby, where its plugin ecosystem, build pipeline, and the GraphQL data layer are developed in the open. Gatsby helped popularize the idea that content-driven sites and blogs could be built with the same component-based tooling as web applications, shaping a generation of static-first React projects.