urql GraphQL Client Library

urql is a highly customizable and versatile GraphQL client for React, Svelte, Vue, Solid, and vanilla JavaScript applications, designed with a modular architecture that starts minimal and adds capabilities through a composable exchange system as application requirements grow. Developed and maintained by Formidable, a global design and engineering consultancy, the library prioritizes lightweight bundle size, logical default behavior, and extensibility over monolithic feature sets. The core client operates as a pipeline of exchanges that intercept, transform, and react to GraphQL operations flowing through the system. The default exchange stack handles fetch execution, deduplication of identical concurrent requests, error normalization, and cache coordination, but developers can insert custom exchanges at any position to implement features like request retrying with exponential backoff, optimistic mutations, authentication token refresh, persisted queries, offline support, subscription multiplexing, and telemetry instrumentation. The document caching exchange provides a simple key-based cache suitable for most applications, while the optional graph cache exchange implements normalized entity caching with automatic cache invalidation based on mutation results, partial data merging, and optimistic updates for mutation responses before server confirmation. Framework bindings expose hooks and components that manage query lifecycle, loading states, error states, pagination, suspense integration, and React 18 concurrent rendering compatibility. The client supports subscriptions over WebSocket through a dedicated exchange, file uploads through the multipart request spec, and SSR hydration for server-rendered applications. TypeScript type generation integrates with GraphQL Code Generator to produce fully typed documents, hooks, and resolver functions. The testing utilities include a mocking framework for defining expected operation responses and asserting execution behavior.