GatsbyJS is a free and open-source static site generator based on React. It uses a modern development stack including Webpack, GraphQL, and modern JavaScript and CSS frameworks. It also provides a rich set of plugins, starters, and themes.
React is a widely used JavaScript library for building user interfaces and single-page applications. It follows a component-based architecture and uses a virtual DOM to efficiently update and render UI components
Documentation themes are built specifically for writing technical and product documentation. They are normally written and maintained in Markdown. The often include a navigation menu, search bar, clear headings, semantic document structure and clean typography.