GraphQL is a query language and runtime for APIs that gives clients the ability to request exactly the data they need – no more and no less – in a single request. Developed as an alternative to traditional REST APIs, GraphQL exposes a single flexible endpoint against which clients send queries specifying precisely which fields and related objects they want. In contrast to REST, where each endpoint returns a fixed data structure and clients often need multiple requests to assemble related data (or receive more data than they need), GraphQL lets the client shape the response, reducing over-fetching and under-fetching and improving efficiency, especially for complex, interconnected data.
GraphQL is built around a strongly typed schema that defines all the types, fields, and relationships available. Clients can query, mutate (write), and subscribe to data through this schema, and the schema itself is often introspectable – meaning clients can query the API to discover its full structure. This flexibility and self-documentation make GraphQL popular for modern applications with rich, relational data needs.
That same flexibility, however, introduces distinctive security considerations, which is why GraphQL appears as a term in an API security context. Because clients can craft arbitrary, deeply nested queries, GraphQL APIs are susceptible to resource-exhaustion and denial-of-service attacks through overly complex or recursive queries that force the server to do excessive work – a concern that maps to the “lack of resources and rate limiting” risk. Introspection, if left enabled in production, can hand attackers a complete map of the API’s schema, aiding reconnaissance. The single-endpoint, flexible-query model complicates traditional security controls that assume fixed REST endpoints, and it can make authorization harder to enforce consistently, since a single query may traverse many types and fields, each of which must be properly authorized – creating room for broken object-level and field-level authorization flaws. Batching and aliasing features can also be abused to amplify attacks such as brute forcing.
Securing GraphQL therefore requires GraphQL-aware measures: enforcing authorization at the field and object level, limiting query depth and complexity, applying rate limiting and query-cost analysis, disabling or restricting introspection in production, validating inputs, and monitoring for abusive query patterns. As GraphQL adoption grows, understanding its unique attack surface – distinct from REST – has become an important part of API security.