Senior Kotlin Engineer — Fintech Microservices Leader

Sii Poland; Kraków; On-site; PLN 180,000 - 260,000; Full time

Benefits offered by this job

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

Job summary

Sii Poland in Kraków is seeking a senior backend engineer to join a fintech platform focused on expense management and real-time financial control. You will design and implement scalable microservices in Kotlin and collaborate with cross-functional teams to deliver integrated solutions for banks, accounting, and HR systems.

The role emphasizes performance analysis, code reviews, mentorship, and architectural improvements to ensure reliability and scalability in a cloud environment such as AWS

Qualifications

• 5+ years of professional software development experience.
• Kotlin expert with microservices and distributed systems experience.
• PostgreSQL, testing with JUnit and Testcontainers, observability with Grafana.
• Strong problem solving and collaboration; mentoring teammates.
• English at least B2; Poland residence required.

Responsibilities

• Lead design, build, and maintain scalable Kotlin-based microservices.
• Collaborate with cross-functional teams across Platform, Services, SMB and more.
• Analyze performance and implement optimizations for reliability and scalability.
• Participate in code reviews and post-mortems; mentor other engineers.
• Drive architectural improvements and migrations.

Skills

Kotlin

Distributed systems

Microservices

Cloud environments (AWS/Kubernetes)

English (B2)

Tools

PostgreSQL

JUnit

Testcontainers

Grafana

Kubernetes

AWS

Job description

Sii Poland in Kraków is seeking a senior backend engineer to join a fintech platform focused on expense management and real-time financial control. You will design and implement scalable microservices in Kotlin and collaborate with cross-functional teams to deliver integrated solutions for banks, accounting, and HR systems.

The role emphasizes performance analysis, code reviews, mentorship, and architectural improvements to ensure reliability and scalability in a cloud environment such as AWS