Senior Kotlin Microservices Engineer – Fintech Platform

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

Benefits offered by this job

Great Place to Work

Centre of internal trainings

Profit sharing

Medical care

Regular integration events

Job summary

Sii Poland is seeking an experienced Senior Backend Engineer to join a fintech platform in Poland. You will design, build, and maintain microservices in Kotlin, supporting integration with banks, accounting systems and HR tools.

You will improve reliability and scalability across AWS/Kubernetes deployments, mentor teammates, and lead architectural migrations. We require 5+ years of software development, strong Kotlin and distributed systems background, PostgreSQL expertise, and English at B2

Qualifications

• 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 PostgreSQL, testing frameworks like JUnit/Testcontainers, and observability tools like Grafana.
• Strong problem-solving skills and a collaborative mindset to mentor teammates.
• Very good knowledge of English - min. B2 level.
• Residing in Poland required.

Responsibilities

• 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

Skills

Kotlin

Microservices

Distributed systems

AWS

Kubernetes

PostgreSQL

JUnit

Testcontainers

Grafana

English (B2)

Job description

Sii Poland is seeking an experienced Senior Backend Engineer to join a fintech platform in Poland. You will design, build, and maintain microservices in Kotlin, supporting integration with banks, accounting systems and HR tools.

You will improve reliability and scalability across AWS/Kubernetes deployments, mentor teammates, and lead architectural migrations. We require 5+ years of software development, strong Kotlin and distributed systems background, PostgreSQL expertise, and English at B2