Juniper is a GraphQL server library for Rust that enables developers to build type-safe and performant GraphQL servers with convenient schema declaration and resolution.
Juniper solves the problem of implementing GraphQL servers in Rust by providing type-safe abstractions that leverage Rust's compiler to catch errors at build time rather than runtime. The library follows a code-first approach, allowing developers to define schemas through Rust code and macros rather than schema files. It supports the full GraphQL specification including interfaces, unions, schema introspection, and validation. A distinctive feature is that Juniper builds non-null types by default, meaning a field of type `Vec<Episode>` becomes `[Episode!]!` in GraphQL, which aligns with Rust's type system philosophy. The library supports both synchronous and asynchronous execution in a runtime-agnostic manner.
Juniper suits projects where type safety and performance are priorities and where developers prefer defining schemas in code rather than through schema files. The library does not include its own web server; instead it provides building blocks for integration with existing frameworks. It offers optional pre-built integrations with Actix, Axum, Hyper, Rocket, and Warp, each including embedded GraphiQL and GraphQL Playground for debugging. Juniper also includes automatic integration with common Rust crates like UUID, URL, Chrono, and BSON, making it straightforward to use these types in schemas. For teams preferring schema-first development, the README names juniper-from-schema as an alternative that generates code from schema files.
The project maintains comprehensive documentation through a book covering guides and examples for all features, alongside API reference documentation. Development activity shows ongoing maintenance with support for multiple web framework integrations and regular updates to align with GraphQL specification changes. The library has not reached version 1.0, so some API instability should be expected as the project continues to evolve.
