What is GraphQL?

GraphQL is an open-source query language for APIs and a runtime for executing those queries, developed by Facebook in 2012 and open-sourced in 2015. Unlike REST APIs where the server determines the response shape, GraphQL lets the client specify exactly what data it needs — nothing more, nothing less. A single GraphQL endpoint replaces multiple REST endpoints. It is strongly typed: every API is described by a schema that defines types and their relationships. GraphQL supports three operation types: queries (read), mutations (write), and subscriptions (real-time). It is transport-agnostic but most commonly served over HTTP.