Senior Backend Developer (Kotlin/Spring Boot)

About the role

We are looking for a Senior Backend Developer with deep expertise in Kotlin and Spring Boot to join a health‑tech initiative building a core FHIR server from scratch. The position is fully remote within Europe and focuses on high‑abstraction backend engineering for healthcare data interoperability.

Key responsibilities

• Design and implement a dynamic query engine that interprets flexible parameters and FHIR structure definitions at runtime.
• Develop and maintain a custom FHIR server using Kotlin, Spring Boot, and PostgreSQL (including JSONB data modeling).
• Collaborate with a small engineering team to define architecture, split tasks, and align on technical direction.
• Write comprehensive automated tests with JUnit and ensure system reliability.
• Integrate healthcare standards such as FHIR R4 and support secure authentication/authorization via OAuth and identity providers.

Required profile

• Strong experience in backend development with Kotlin and/or other JVM‑based technologies.
• Hands‑on production experience with Spring Boot.
• Proven ability to build high‑abstraction systems such as query or rule engines.
• Advanced knowledge of PostgreSQL, including complex queries and JSONB.
• Fluent English communication (minimum B2) and ability to work remotely in a distributed team.

Required skills

• Kotlin
• Spring Boot
• PostgreSQL
• JSONB
• JUnit
• FHIR R4 (HL7 FHIR, HAPI FHIR)
• OAuth
• Zitadel (identity provider)
• SpiceDB (authorization system)

What we offer

• Competitive senior‑level compensation.
• Fully remote work within Europe with flexible collaboration.
• Opportunity to shape a critical component of modern healthcare data infrastructure.