GraphQL Kotlin
GraphQL Kotlin is a free collection of libraries built on graphql-java for running GraphQL clients and servers in Kotlin.
What GraphQL Kotlin is
GraphQL Kotlin is a free collection of libraries built on graphql-java for running GraphQL clients and servers in Kotlin. Its schema generator creates a GraphQL schema from Kotlin code, and a federation module can generate Apollo Federation compliant schemas. Gradle and Maven plugins generate type-safe Kotlin client code from an existing schema. Generated clients support queries, mutations, batching, coroutines, custom scalars, and configurable enum defaults; generated models support Jackson and kotlinx.serialization. Reference HTTP clients use Ktor HTTP Client and Spring WebClient, though custom implementations can use other engines. Server implementations are available for Spring Boot and Ktor, with Spring using Spring WebFlux. Ktor supports Kotlin Flow subscriptions over WebSockets using graphql-transport-ws. Its plugin leaves route setup to the application, which can selectively enable routes and add logic such as authentication. The schema generator supports Kotlin Lists, but Sets, arbitrary Maps, and arrays are not supported out of the box. The library uses the Apache License 2.0.
Good
- Free under Apache License 2.0.
- Generates schemas and type-safe Kotlin clients.
- Supports queries, mutations, batching, and coroutines.
- Offers Spring Boot and Ktor server implementations.
- Supports Jackson and kotlinx.serialization models.
Watch out
- Ktor routes require explicit configuration.
- Sets, arbitrary Maps, and arrays lack out-of-box support.
Who it suits
GraphQL Kotlin suits Kotlin teams building GraphQL servers or generating type-safe clients from existing schemas. It fits teams using its supported frameworks and collection types or willing to handle route configuration themselves.
Verdict
GraphQL Kotlin covers both server and client work in Kotlin, with framework integrations and generated types. Check collection support and route setup needs when assessing fit.
Plans and prices
From GraphQL Kotlin's own pricing page, checked 4 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Open source | Free | Apache License 2.0 |
The facts
Each one read from GraphQL Kotlin's own pages, with the date it was checked.
What it does
- Client features
- Clients support query and mutation operations, batching, coroutines, custom scalars, and configurable enum defaults.checked 4 Oct 2026
- Client generation
- Gradle and Maven plugins generate type-safe Kotlin client code from an existing GraphQL schema.checked 4 Oct 2026
- Client integrations
- Reference HTTP client implementations use Ktor HTTP client and Spring WebClient, and custom implementations can use other engines.checked 4 Oct 2026
- Collection limit
- The schema generator explicitly supports Kotlin Lists; Sets, arbitrary Maps, and arrays are not supported out of the box.checked 4 Oct 2026
- Configuration limit
- The Ktor plugin does not automatically configure routes; routes must be explicitly configured with the Routing plugin.checked 4 Oct 2026
- Federation
- The federation module can generate Apollo Federation compliant schemas.checked 4 Oct 2026
- Integrations
- Reference client implementations use Ktor HTTP Client and Spring WebClient, and custom implementations can use other engines.checked 4 Oct 2026
- Intended users
- The project describes its common use cases as running a GraphQL server and generating a type-safe client in Kotlin.checked 4 Oct 2026
- License
- The library is licensed under Apache License 2.0.checked 4 Oct 2026
- Purpose
- GraphQL Kotlin is a collection of libraries built on graphql-java to run GraphQL clients and servers in Kotlin.checked 4 Oct 2026
- Schema generation
- Its schema generator creates a GraphQL schema from Kotlin code and can expose it through a server library.checked 4 Oct 2026
- Security
- The repository README directs users to SECURITY.md for security issue contact information and supported versions receiving security updates.checked 4 Oct 2026
- Security policy
- The repository directs users to its security policy for reporting issues and information about versions receiving security updates.checked 4 Oct 2026
- Serialization
- Generated client models support Jackson and kotlinx.serialization formats.checked 4 Oct 2026
- Server configuration
- The Ktor plugin does not configure routes automatically, allowing applications to selectively enable routes and wrap them with logic such as authentication.checked 4 Oct 2026
- Server frameworks
- The documentation describes server examples and integrations for Spring Boot and Ktor.checked 4 Oct 2026
- Server integrations
- The project provides Spring Boot and Ktor server implementations; the Spring server uses Spring WebFlux.checked 4 Oct 2026
- Subscriptions
- The Ktor server supports Kotlin Flow subscriptions over WebSockets using the graphql-transport-ws subprotocol.checked 4 Oct 2026
- Support
- The maintainers invite questions through GitHub Discussions and the public #graphql-kotlin channel on Kotlin Slack.checked 4 Oct 2026
- What it does
- GraphQL Kotlin is a collection of libraries built on graphql-java for running GraphQL clients and servers in Kotlin.checked 4 Oct 2026
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