Senior Kotlin Engineer – Fintech Microservices Lead

Sii Poland; Łódź; 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

Many experts you can learn from

Open and accessible management team

Job summary

Sii Poland is building a modern fintech platform that enables expense management and seamless integration of financial tools into partner systems, including banks, accounting platforms, and HR solutions. The team focuses on scalable microservices and strong engineering practices to deliver real-time control over company spending.

You will design, build, and maintain Kotlin-based microservices, mentor peers, and drive architecture improvements while working with AWS, Kubernetes, PostgreSQL, and

Qualifications

• 5+ years of professional software development experience.
• 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 teammates.
• Very good knowledge of English - min. B2 level.
• Residing in 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 high reliability and scalability.
• Participate in code reviews, post-mortems, and mentor other engineers.

Skills

Kotlin

Distributed systems

Microservices

AWS

Kubernetes

PostgreSQL

JUnit

Testcontainers

Grafana

English B2

Poland resident

Tools

PostgreSQL

Job description

Sii Poland is building a modern fintech platform that enables expense management and seamless integration of financial tools into partner systems, including banks, accounting platforms, and HR solutions. The team focuses on scalable microservices and strong engineering practices to deliver real-time control over company spending.

You will design, build, and maintain Kotlin-based microservices, mentor peers, and drive architecture improvements while working with AWS, Kubernetes, PostgreSQL, and