Senior Full Stack Engineer (d/f/m)

This is a hybrid role, and our office is based in Berlin Charlottenburg.

Responsibilities

• Full-stack feature development: Design and implement end-to-end features across our Spring Boot backend services and Astro/React frontend applications, ensuring scalability, performance, and maintainability
• Growth experimentation: Build and iterate on conversion-focused features, A/B testing infrastructure, and data-driven optimizations that directly impact our subscriber growth metrics
• System design and architecture: Shape technical solutions for complex growth features, making informed decisions about API design, data modeling, and integration patterns while considering security, cost, and long-term maintainability
• Cross-functional collaboration: Partner closely with Product, Business Development, and Data teams to translate growth hypotheses into technical solutions, communicating trade-offs clearly and driving alignment
• Technical excellence and mentoring: Establish testing standards, monitoring practices, and quality benchmarks for growth initiatives. Share knowledge and mentor team members in full-stack development practices

Requirements

• 5+ years of professional software development experience
• Proven track record of AI-supported delivery in backend and frontend
• Experience working in cross-functional product teams, ideally in growth, e-commerce, or B2B platforms
• Solid backend experience with Java/Kotlin and Spring Boot ecosystem, building RESTful APIs and working with relational databases (PostgreSQL & DynamoDB)
• Strong experience with modern JavaScript/TypeScript, React, and contemporary frontend tooling. Familiarity with Astro, TailwindCSS, or similar frameworks is a plus
• System thinking: Understanding of microservices architecture, API design principles, and distributed system patterns
• DevOps awareness: Experience with CI/CD pipelines, observability tools (monitoring, logging, metrics), and cloud infrastructure basics
  

  Ways of Working:

  • Product mindset: You connect technical decisions to business outcomes, understand how to balance speed with quality, and can identify systemic risks in growth-focused development

  • Communication: You explain technical trade-offs clearly to non-technical stakeholders and foster alignment across teams and functions

  • Ownership: You take responsibility for your systems' long-term health, considering dependencies, costs, and maintainability in your decision-making

  • Growth mindset: You seek feedback proactively, stay current with emerging technologies (especially AI-assisted development tools), and contribute to team learning

Benefits

At Kleinanzeigen, we care about our people — their wellbeing, growth, and life beyond work. Our benefits are designed to support you holistically, giving you flexibility and opportunities to thrive.

✨ Flexibility

• Flexible working time (hybrid)

• 20 days “work from anywhere”

• Paid additional parental leave for both parents

• Extra paid days off for special occasions (e.g. your wedding or a move)

❤️‍🩹 Wellbeing & Support

• Confidential support & coaching for you and your loved ones

• Annual company sports events

• Pension and life insurance

📚 Growth & Development

• Personal development budget

• Learning opportunities to grow your skills and career
  

🛍️ Perks & Everyday benefits

• Corporate benefits and exclusive discounts

• An attractive referral program

• Transportation allowance

• Free shipping on Kleinanzeigen Direktkauf

Kleinanzeigen is an equal opportunity employer that values diversity and inclusion. We welcome people of all backgrounds, races, religions, colours, national origins, gender identities, sexual orientation, ages, marital status, or disability.

If this role sparks your interest but you’re not sure you meet every single requirement, we’d still love to hear from you anyway.