kotlin developer for Bookings

SumUp provides simple and affordable business tools that help more than 4 million small businesses across 36 markets start, run, and grow. Its financial tools support payments, finance, and customer relationships, while the Sell Online Tribe develops Online Store and Bookings products that help merchants manage appointments, showcase offerings, and accept payments.

• Design, build, and maintain scalable backend systems supporting SumUp’s Bookings product;
• Collaborate with frontend and mobile engineers to deliver new features and improve APIs across web, iOS, and Android;
• Participate in technical planning, code reviews, and design discussions to ensure clean, testable, and maintainable code;
• Continuously optimise performance, ensure observability, and uphold high reliability standards;
• Contribute to shaping the technical roadmap for the Sell Online platform.

• Have 5+ years of professional backend engineering experience;
• Be fluent in Kotlin or Java and have deep experience with Spring Boot;
• Have experience with PostgreSQL, Kafka, Docker, Kubernetes, and AWS;
• Understand RESTful APIs, distributed systems, and event-driven architectures such as CQRS and Event Sourcing;
• Have experience with CI/CD pipelines, GitHub Actions, and observability tools such as Grafana or Honeycomb;
• Thrive in collaborative teams, mentor peers, and care about delivering real value to merchants;
• Nice to have: familiarity with gRPC, Protobuf, or backend/database-level performance optimisation.

• Salary range: 18 850 - 29 660 PLN per month;
• Virtual Stock Option programme;
• Annual L&D budget of €2000 for conferences and further education;
• Fitness support, including an on-site gym and a subsidised Multisport Card;
• Health insurance coverage for the employee and family, plus life insurance;
• 26 Days of paid leave plus public holidays and special leave days;
• One-month sabbatical after 3 years of service;
• Referral Bonus.