GraphQL

GraphQL is a query language and runtime for APIs that lets clients request exactly the data they need in a single request, eliminating the over-fetching and under-fetching problems common with REST endpoints. Developed at Facebook in 2012 and open-sourced in 2015, it has become a standard approach for applications with complex or nested data requirements.

Unlike REST, where the server determines the shape of each response, GraphQL puts the client in control. A frontend developer writes a query specifying the exact fields needed, and the server returns precisely that data structure. This is particularly valuable for mobile applications on slow networks and for pages that aggregate data from multiple related entities in a single view.

The type system is a core strength. Every GraphQL API is defined by a schema that describes available types, fields, and relationships. This schema serves as both documentation and a contract between frontend and backend teams. Tools like GraphQL Playground and Apollo Studio let developers explore the schema interactively, test queries, and catch errors before writing application code. Real-time subscriptions and built-in introspection further extend its capabilities for modern web applications.