I’ve briefly mentioned before that GitHub joined the adopters of the GraphQL for their API. Here’s the link to the full documentation and more details.
GitHub chose GraphQL for our API v4 because it offers significantly more flexibility for our integrators. The ability to define precisely the data you want—and only the data you want—is a powerful advantage over the REST API v3 endpoints. GraphQL lets you replace multiple REST requests with a single call to fetch the data you specify.