Relay

Relay is data-fetching turned declarative. Components declare their data dependencies, without worrying about how to fetch them. Relay guarantees that the data each component needs is fetched and available. This keeps components decoupled and promotes reuse. With Relay, components and their data dependencies can be quickly modified without modifying other parts of the system. That means you won't accidentally break other components as you refactor or make changes to your app. Relay's compiler aggregates and optimizes the data requirements for your entire app, so that they can be efficiently fetched in a single GraphQL request. Relay handles the heavy lifting to ensure the data declared by your components is fetched in the most efficient way. For example, by deduplicating identical fields, and precomputing information used at runtime, among other optimizations. Relay also supports executing GraphQL Mutations, optionally with optimistic updates, and updates to local data.