# Java SDK

Canonical page: https://docs.ovok.com/java-sdk

Use the Java SDK to call Ovok Core from Java 17 or later. The `Ovok` client signs users in, refreshes their tokens, and exposes FHIR R4, measurements, Slim, Signals, platform, and CMS routes as namespaces. Responses are Jackson 3 `JsonNode` values, so you can bind them to your own models.

- [Get started](/java-sdk/getting-started): install, configure, sign in, and read a FHIR resource.
- [Client configuration](/java-sdk/client-configuration): options, session storage, and machine clients.
- [Errors and retries](/java-sdk/errors-and-retries): exceptions, request options, and retries.
- [Measurements](/java-sdk/measurements): save device readings as Observations.
- [Compatibility](/java-sdk/compatibility): the original `OvokClient` and requirements.

Each namespace has its own page, starting with [authentication](/java-sdk/authentication), [FHIR](/java-sdk/fhir-and-observations), [patient](/java-sdk/patient), and [Slim](/java-sdk/slim-apis). The [API reference](/java-sdk/reference) lists every class and method; it is generated from the Javadoc.