GatsbyJS is a site generator that uses modern web technologies to produce in their words "blazing fast websites and apps".
It is based on the React JavaScript framework from Facebook and uses Webpack, GraphQL and the latest development techniques to provide really fast user experiences.
Primer is the design system built by, and for GitHub. It encompasses everything from Iconography and Web Components, through to the companies presentation master slides. We use a small subset of their open-source tools which are detailed below.
Doctocat is the GatsbyJS theme GitHub have developed for their documentation. It is preconfigured for working within the Primer team, so requires some modification out-of-the-box to remove branding etc.
It also contains a number of useful components and datasources that link back to GitHub data such as the list of Contributors at the bottom of each page.
MDX is Markdown for the component era. It lets you write JSX embedded inside Markdown. It's a great combination because it allows you to use Markdown's terse syntax (such as `# Heading`) for your content and JSX for more advanced, or reusable components.