The Stitch IDE includes an interactive schema explorer which includes API reference docs available here. Click the tab labeled Docs on the top right to open the explorer. Visit this page for more information on how the IDE works.
GraphQL Specification is the official specification of the GraphQL language.
GraphQL Learn provides a more approachable introduction to GraphQL.
Stitch aims to maintain compatibility with the Relay Server Specification.
Stitch currently uses Apollo Server to serve API requests.