Backend Developer

This role is part of a highly technical healthtech initiative focused on rebuilding a core FHIR server from the ground up. You will be working on complex, abstraction-heavy backend engineering challenges, going far beyond standard API development. The primary focus is the design and implementation of a dynamic query engine capable of interpreting flexible parameters and FHIR structure definitions at runtime. You will join an existing team of engineers and contribute to a shared architecture, working collaboratively on design decisions and system evolution. The environment is deeply technical, with strong emphasis on scalability, correctness, and healthcare interoperability standards. This is a hands-on role where your work will directly influence the backbone of modern healthcare data infrastructure. Accountabilities: Design and implement high-abstraction backend components, with a focus on a dynamic query engine for FHIR-based data structures Contribute to the development of a custom FHIR server built in Kotlin and Spring Boot Collaborate with a small engineering team to define architecture, split tasks, and align on technical direction Develop and maintain robust backend services using PostgreSQL, including JSONB-based data modeling and complex queries Build and expand comprehensive automated test coverage using JUnit to ensure system reliability Integrate and work with healthcare data standards such as FHIR R4 where applicable Participate in technical discussions, surfacing blockers and refining system design with the team Support secure authentication and authorization patterns using OAuth and identity management systems Ensure backend systems are scalable, maintainable, and aligned with long-term platform goals

Strong experience in backend development using Kotlin and/or JVM-based technologies Solid hands-on experience with Spring Boot in production environments Proven ability to build or contribute to high-abstraction systems such as query engines, rule engines, or dynamic processing frameworks Strong knowledge of PostgreSQL, including advanced querying and JSONB data modeling Experience writing and maintaining comprehensive automated test suites using JUnit Ability to work collaboratively within a small engineering team and align on shared architectural decisions Strong communication skills with fluent English (minimum B2 level) for daily technical collaboration Comfortable working remotely within Europe and engaging in distributed team workflows Bonus: familiarity with HL7 FHIR (R4), HAPI FHIR, or healthcare data systems Bonus: experience with OAuth flows, identity providers such as Zitadel, or authorization systems like SpiceDB

Competitive compensation aligned with senior-level expertise Fully remote work within Europe with flexible collaboration Opportunity to work on a cutting-edge healthcare infrastructure project Exposure to complex, real-world FHIR and healthcare interoperability challenges Close collaboration with experienced engineers in a highly technical environment Strong influence on architecture and system design decisions Long-term engineering impact on a critical healthcare data platform International, collaborative, and engineering-driven culture How Jobgether works

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Backend Developer (Kotlin/Spring Boot) based in Spain.