Apollo Client vs GraphQL Kotlin

Apollo Client is a JavaScript library for managing GraphQL data in applications. It can fetch, cache and modify data from local and remote sources, then update the interface as data changes. Developers describe a query and receive its data without manually managing loading states. Normalized caching can make responses to cached queries almost immediate. The core @apollo/client library has built-in React integration, including hooks and Suspense, and the library can be added incrementally to JavaScript or TypeScript applications. It works with any build setup and GraphQL API. Community integrations extend support to frameworks including Angular, Vue, Svelte, Solid.js and Ember, as well as native iOS and Android. Apollo Client also supports GraphOS Router features such as incremental delivery, subscriptions and persisted-query safelisting. Chrome and Firefox extensions provide GraphiQL and tools for inspecting watched queries, mutations and cache. Apollo Client is free and open source. GraphOS Free includes one self-hosted router limited to 60 requests per minute; the separate Developer plan is $5 a month, billed monthly.

GraphQL Kotlin is a free Apache License 2.0 collection of libraries, built on graphql-java, for running GraphQL clients and servers in Kotlin. Its schema generator creates schemas from Kotlin code, and a federation module can produce Apollo Federation-compliant schemas. Gradle and Maven plugins generate type-safe Kotlin clients from existing schemas. Generated clients support queries, mutations, batching, coroutines, custom scalars, configurable enum defaults, and Jackson or kotlinx.serialization models. Reference HTTP integrations use Ktor HTTP Client and Spring WebClient, while custom engines are possible. Server implementations target Spring Boot and Ktor; the Spring server uses Spring WebFlux. Ktor supports Kotlin Flow subscriptions over WebSockets with the graphql-transport-ws subprotocol. Its plugin leaves route configuration to the application, allowing selective routes and added authentication logic. The schema generator supports Kotlin Lists, but Sets, arbitrary Maps, and arrays are not supported out of the box. The project is self-hosted, with security guidance in its repository and community support through GitHub Discussions and Kotlin Slack.