TypeSafeClient, ApiKey, TypeSafeException, the wire DTOs, and the JsonCodec/HttpTransport SPIs. Zero dependency on any particular JSON or HTTP library — plug in typesafe-java-jackson2/typesafe-java-jackson3 and typesafe-java-client-jdk (or your own implementations). The DTOs and JsonCodec SPI alone are also reusable by any other integration (e.g. a Kafka producer/consumer) that needs to (de)serialize TypeSafe payloads.