Kotlin Developer (f/m/x)

Join a team working on a modern fintech platform that supports company expense management. The project focuses on developing a finance solution that enables seamless integration of financial tools (including payment cards, expense management, and invoice handling) directly into partner systems such as banks, accounting platforms, and HR solutions. The product being developed allows companies to simplify financial processes, automate settlements, and gain full real-time control over their spending.
Your tasks
Leading initiatives to design, build, and maintain scalable microservices primarily using Kotlin
Collaborating with cross-functional teams to develop innovative solutions across Platform, Services, SMB, and other domains
Analyzing system performance and implementing optimizations to ensure high reliability and scalability
Participating in code reviews, post-mortems, and providing mentorship to other engineers
Proactively improving the architecture and quality of solutions, and leading the team through technical challenges and migrations
Requirements
Minimum 5 years of professional experience in software development
Expertise in server-side languages, especially Kotlin, and experience with distributed systems, microservices, and cloud environments (e.g., AWS, Kubernetes)
Proficiency with relational databases like PostgreSQL, testing frameworks (e.g., JUnit, Testcontainers), and observability tools like Grafana
Strong problem-solving skills and a collaborative mindset to mentor and upskill your teammates
Very good knowledge of English - min. B2 level
Residing in Poland required
Nice to have
Previous work in the fintech industry or with financial products
Knowledge of topics related to payments, cards, or accounting
Experience working in a scale-up environment
Proficiency in one of the following front-end technologies: React or TypeScript
Job no. JOB-EQKGG
Sii ensures that all hiring decisions are made solely on the basis of qualifications and competence. We are committed to equal and fair treatment of all, regardless of legally protected characteristics. At Sii, we promote a diverse and inclusive work environment, in full compliance with applicable anti-discrimination laws.
Benefits For You
Great Place to Work
Solid financial situation
Contracts with the biggest brands
Centre of internal trainings
Many experts you can learn from
Open and accessible management team
Profit sharing
Passion Sponsorship program
Regular integration events and trips
Comfortable and well-equipped offices
MySii app
Medical care

Work arrangement
Yes