Fullstack/Back End Developer (Freelance/Berlin/Hybrid)

Senior Full-Stack / Backend Engineers (Contract) – HealthTech SaaS

Location: Berlin or nearby (occasional on-site: ~1 week every 3 months)

Start Date: ASAP

Contract Type: Freelance / Contract (Conversion to Perm employment possible)

🚀 About the Role

Join a fast-growing, Berlin-based healthtech SaaS company transforming how medical practices manage administrative and financial workflows.

You will be working on WorkOS — a client-facing operational system used by doctors to manage their day-to-day workflows. This is a mission-critical product with direct impact on how medical professionals operate and interact with patients and administrative processes.

This is a high-impact role where your work will be immediately visible to end users (medical professionals).

🛠️ What You’ll Do

• Drive the transition from monolith to microservices architecture
• Improve system reliability and performance, reducing production incidents
• Work on backend systems powering the doctor-facing operational platform
• Collaborate closely with product, design, and client-facing teams
• Integrate and maintain REST APIs across systems
• Contribute to a scalable, high-performance architecture
• Own and optimize services built in Node.js

✅ What You Bring

Required

• Strong hands-on experience with TypeScript, React, Next.js, and Node.js
• Solid experience working with REST APIs
• Proven ability to work cross-functionally in product-driven teams
• Fluent in English
• Self-starter mindset with the ability to operate autonomously in fast-paced environments

Nice to Have

• Experience with LLMs / AI engineering
• Familiarity with Python
• German language skills
• Previous experience in SaaS or healthtech environments

🏗️ Tech Environment

• Frontend: React, Next.js
• Backend: Node.js (core focus)
• Architecture: Transitioning from monolith → microservices
• Integrations: REST APIs, external systems
• Product Context: Doctor-facing operational SaaS platform

🎯 Interview Process

• 30 min intro call (Engineering Manager / Irina)
• 1-hour live coding session
• 1-hour system design interview