Senior Backend Engineer

We are looking for a Senior Backend Engineer to join our Team Lake, one of several teams within our Customer-Facing Department. Our current initiatives include building a dynamic intelligence tool that directly impacts our buying and selling strategies. Also the team owns key parts of our customer experience — making buying and selling refurbished electronics seamless and enjoyable. We're a team of passionate engineers, a creative designer, and a focused product manager, all working together to bring sustainable choices to thousands of users every day. As a (Senior) Backend Engineer, you'll be shaping the backbone of rebuy.de , directly influencing how customers interact with our platform. You won't just maintain existing systems, you'll build elegant, scalable solutions that grow with us, iterating fast based on real user feedback. You'll take ownership beyond code: open communication, giving and receiving feedback respectfully and helping others succeed. You'll primarily work with Kotlin and PHP (Symfony) within our service-oriented architecture and occasionally support the frontend (Angular) when needed. If you thrive in a dynamic, tech-driven environment and enjoy working with cross-functional teams, we would love to hear from you Ready to become part of the most important mission on this planet? We are rebuy, pioneers in the sustainable reuse of electronics and media and we are looking for you Our mission: to make circular living accessible to all, one transaction at a time. By giving products a second chance, we reduce resource consumption and avoid unnecessary e-waste. Our team of 600 comes from all corners of the world; we drive things forward collaboratively, take personal responsibility, value positive critical thinking, and persistently serve our customers and planet. Design, build and maintain backend services with Kotlin and PHP (Symfony) Work on a high-traffic platform, optimizing for performance, stability and scale Ship fast, favoring MVPs and rapid iteration based on customer feedback Help improve our architecture and backend practices continuously Actively contribute ideas in technical discussions and cross-functional planning Collaborate closely with designers and frontend developers to build features from idea to production At least 7 years of experience in backend development, with proven expertise in Kotlin and PHP/Symfony, and the ability to work independently with both technologies You are experienced in building and scaling service-oriented architectures in a high-scale, high-traffic environment You enjoy working closely with frontend engineers, product managers, and designers As a Senior Engineer, we expect you to combine technical expertise with maturity in collaboration and ownership. You won't have direct reports, but your impact will shape how the team moves forward You are an effective communicator who values transparency and team spirit You are pragmatic: you prioritize shipping working solutions and iterating quickly You like contributing ideas, improving processes, and shaping better user experiences Bonus: you feel comfortable occasionally working on frontend tasks (Angular) Work with a friendly team that is passionate about circularity and wants to make the world a little more sustainable, one transaction at a time Feel comfortable in an environment where independence and new ideas are welcome Benefit from flat hierarchies and the greatest possible transparency so that things don't take longer than they have to and you always feel well informed Enjoy our centrally located office in Berlin (Erkelenzdamm 11 - 13, 10999 Berlin) Benefit from our family-friendly, flexible environment and paid child sick leave Bring your dog to the office: we love animals and want to cuddle yours, too Use employee discounts on rebuy.de, sustainable products at Futurebens, offers for sustainable micro-mobility and massages directly in our office Have fun at our legendary team and company events Use our mental health offers as part of a cooperation with nilo Take care of your work-life balance with 30 vacation days *At rebuy all people are welcome and supported We would like to talk, regardless of age, disability, national and social origin, skin color, religion, gender identity and sexual orientation. Just be who you are. Working hours: Full time Location: Berlin Hybrid model