Senior Software Engineer - Fullstack - Ratepay GmbH

At Ratepay, we develop next-generation payment solutions that power the checkout experience for some of Germany’s largest online retailers and marketplaces. As a Senior Software Engineer (m/f/d), you’ll play a key role in building secure, scalable, and user-friendly Buy Now, Pay Later products in a dynamic and fast-growing e-commerce sector.

You’ll join a collaborative, agile team dedicated to enabling seamless commercial and technical onboarding of merchants, marketplaces, and resellers. Our focus is on modern integrations, fast onboarding, and intuitive configuration—making it easy for merchants to go live quickly while also improving the experience for internal Ratepay teams involved in the process.

Tasks

• You take ownership of the design, development, operation and continuous improvement of our systems, ensuring high performance and stability.
• You integrate internal and external APIs within a modern microservice architecture, with scalability and maintainability in mind.
• You contribute actively to our agile software engineering process, collaborating with cross-functional teams including Product, Infrastructure, and Risk.
• You mentor and support junior engineers, sharing knowledge and fostering a culture of learning and growth.
• You bring in your ideas and technical experience to continuously challenge the status quo and drive innovation within the team.
• You will be responsible for operational success of the teams services also being on call.

Requirements

• You have 6+ years of hands-on experience in Java backend development, with Kotlin being a plus.
• You possess solid frontend skills using Vue.js or another modern JavaScript framework.
• You are proficient in Spring/Spring Boot, Docker, Git, and Maven.
• You have experience building and deploying applications in cloud environments, preferably AWS.
• You have strong database knowledge, especially with PostgreSQL, and some familiarity with MongoDB or Redis is a plus.
• You understand RESTful APIs, OAuth2, event-driven architectures like Kafka, and microservices.
• Ideally, you are familiar with Kafka Streams and contract testing tools such as PACT.
• You are comfortable working in agile teams and embrace a DevOps mindset: “you build it, you run it.”
• Experience in fintech or risk-related systems would be an additional advantage.

At Ratepay, you’ll work in an environment built on trust, ownership, and collaboration. We believe in empowering engineers with autonomy, modern tooling, and the space to make meaningful technical decisions. You’ll work closely with experienced colleagues from diverse backgrounds, benefit from transparent communication, and have the opportunity to grow both personally and professionally. We value balance, flexibility, and a healthy work culture—because great products are built by teams that