Senior Backend Developer (Kotlin/Go) – Focus Mass Data & Health

Project overview

About the Project and the Client

For our client, a highly innovative, European-focused cloud provider and IT service provider in the enterprise environment, we are looking for experienced freelance support starting immediately. The project revolves around the new development and scaling of a backend for managing app data, with a strong focus on the secure and extremely performant processing of sensitive health data.

The project is handled by a small, effective agile team (max. 5 developers, 1 PO, 1 Business Analyst) in Scrum mode, and you will have the opportunity to significantly shape a data-intensive architecture from the beginning.

Responsibilities

Skills

Must-Have Requirements

Nice-to-have (Bonus Points)

• Backend Development: Conception and development of robust backend services for general data management for apps, primarily in the health sector (data from fitness trackers and large medical devices).
• API Design & Mass Data: Building high-performance REST APIs designed for the extremely fast reception of huge amounts of data and a very high number of concurrent users.
• Data Processing & Analysis: Ensuring the performant persistence of mass data and the development of logic for the rapid provision of data analyses.
• AI Integration: Conceptual and technical use of AI technologies in the further course of the project.
• Frontend Support (Future): Subsequent support in building an internal admin frontend.
• In-depth, multi-year project experience in backend development with Kotlin.
• Proven expertise in handling and persisting mass data, as well as in building highly scalable REST APIs.
• Fluent or very good German language skills, spoken and written.
• Strong communication skills and a pragmatic, hands-on mentality: You are comfortable with a dynamic environment, initial uncertainties, and spontaneous planning changes.
• Project experience with Go (Golang), as individual services will be implemented in this language.
• Previous experience in HealthTech / health data.
• Willingness or initial practical experience in integrating AI solutions.
• Experience with Vue.js (specifically Vue.js design systems) for the later admin frontend.

Project details

• Start: 04.11.2026
• Duration: 6 Monate
• Location: 74072 Heilbronn, Neckar, DE
• Languages: German