Senior Kotlin Engineer - Fintech Microservices & Scale

Sii Poland; Rzeszów; On-site; PLN 200,000 - 320,000; Full time

Benefits offered by this job

Great Place to Work

Centre of internal trainings

Profit sharing

Medical care

Open and accessible management

Job summary

Sii Poland is building a modern fintech platform that enables seamless integration of financial tools into partner systems. You will lead Kotlin-based microservices, scale architectures, and drive reliability while mentoring engineers in a collaborative, fast-growing environment.

Join a team delivering real-time spending controls and automated settlements, with strong emphasis on performance, observability, and cross-functional collaboration across Platform, Services, and SMB domains.

Qualifications

• 5+ years of professional software development.
• Expertise in server-side languages, especially Kotlin, with distributed systems and microservices.
• Experience with cloud environments (AWS, Kubernetes).
• Proficiency with PostgreSQL and testing frameworks (JUnit, Testcontainers) and observability tools like Grafana.
• Strong problem-solving and collaboration; able to mentor teammates.
• English level minimum B2; residents of Poland required.

Responsibilities

• Lead initiatives to design, build, and maintain scalable microservices primarily using Kotlin.
• Collaborate with cross-functional teams to develop solutions across Platform, Services, SMB, and other domains.
• Analyze system performance and implement optimizations for reliability and scalability.
• Participate in code reviews, post-mortems, and mentor other engineers.
• Proactively improve architecture and quality, guiding the team through challenges and migrations.

Skills

Kotlin

Distributed systems

Microservices

Cloud (AWS/Kubernetes)

PostgreSQL

Testing (JUnit/Testcontainers)

Grafana

Mentorship

English (B2)

Job description

Sii Poland is building a modern fintech platform that enables seamless integration of financial tools into partner systems. You will lead Kotlin-based microservices, scale architectures, and drive reliability while mentoring engineers in a collaborative, fast-growing environment.

Join a team delivering real-time spending controls and automated settlements, with strong emphasis on performance, observability, and cross-functional collaboration across Platform, Services, and SMB domains.