GraphQL is an open-source query language and runtime for APIs that enables clients to request exactly the data they need in a single request. Developed by Facebook in 2012 and released publicly in 2015, GraphQL provides a flexible alternative to REST APIs by allowing developers to define the structure of the response, eliminating the common problems of over-fetching and under-fetching data.
In a GraphQL API, the server exposes a strongly typed schema that describes all available data types, queries, and mutations. Clients send queries that mirror the shape of the desired response, and the server returns precisely that structure. This approach is particularly valuable for mobile and frontend applications where bandwidth efficiency and reducing the number of network requests are critical for performance.
GraphQL has been widely adopted by companies such as GitHub, Shopify, and Twitter for their public and internal APIs. Its ecosystem includes tools like Apollo Client, Relay, and Hasura that simplify implementation on both the client and server sides. While GraphQL introduces complexity in areas like caching and rate limiting compared to REST, its flexibility and developer experience make it a popular choice for modern application architectures.