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 focused on rebuilding a core FHIR server from scratch. The role is fully remote within Europe and will involve tackling high‑abstraction backend challenges that go far beyond standard API work.

Key responsibilities

• Design and implement a dynamic query engine for FHIR‑based data structures.
• Develop and maintain a custom FHIR server using Kotlin and Spring Boot.
• Collaborate with a small engineering team on architecture, task division, and technical direction.
• Build robust backend services with PostgreSQL, leveraging JSONB for flexible data modeling.
• Write comprehensive automated tests with JUnit to ensure reliability.
• Integrate healthcare standards such as FHIR R4 and support OAuth‑based authentication and authorization.

Required profile

• Strong experience in backend development with Kotlin and/or JVM technologies.
• Hands‑on production experience with Spring Boot.
• Proven ability to create high‑abstraction systems like query or rule engines.
• Deep knowledge of PostgreSQL, including advanced queries and JSONB.
• Experience writing automated test suites using JUnit.
• Fluent English communication (minimum B2) and ability to work remotely in a distributed team.

Required skills

• Kotlin
• Spring Boot
• PostgreSQL
• JSONB
• JUnit
• FHIR (R4)
• OAuth
• Identity management systems

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.