Senior Kotlin Engineer - Fintech Microservices

Sii Poland; Lublin; On-site; PLN 180,000 - 240,000; Full time

Benefits offered by this job

Great Place to Work

Profit sharing

Medical care

Centre of internal trainings

Office in Poland

Open management team

Job summary

Sii Poland is seeking a senior backend engineer to join a modern fintech platform that supports company expense management. The project focuses on developing a finance solution that enables seamless integration of financial tools into partner systems such as banks, accounting platforms, and HR solutions.

You will design, build, and maintain scalable microservices in Kotlin, collaborate with cross-functional teams, optimize performance, mentor engineers, and lead migrations while contributing to

Qualifications

• Minimum 5 years of professional software development experience.
• Proficient in Kotlin and server-side architectures.
• Experience with distributed systems, microservices, and cloud environments (AWS/Kubernetes).
• Strong English skills (min B2) and collaborative mindset.
• Residing in Poland is required.

Responsibilities

• Lead design, build, and maintenance of scalable microservices.
• Collaborate with cross-functional teams across Platform, Services, SMB, and other domains.
• Analyze system performance and implement optimizations for reliability and scalability.
• Participate in code reviews, post-mortems, and mentorship of other engineers.
• Proactively improving architecture and leading migrations and technical challenges.

Skills

Kotlin

Microservices

Cloud (AWS/Kubernetes)

PostgreSQL

Testing (JUnit/Testcontainers)

English (B2+)

Leadership/Mentoring

Tools

Kubernetes

PostgreSQL

Grafana

JUnit

Testcontainers

Job description

Sii Poland is seeking a senior backend engineer to join a modern fintech platform that supports company expense management. The project focuses on developing a finance solution that enables seamless integration of financial tools into partner systems such as banks, accounting platforms, and HR solutions.

You will design, build, and maintain scalable microservices in Kotlin, collaborate with cross-functional teams, optimize performance, mentor engineers, and lead migrations while contributing to