Senior Kotlin Engineer - Fintech Microservices & Scale

Sii Poland; Województwo pomorskie; On-site; PLN 300,000 - 420,000; 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 is hiring a senior software engineer to join a fintech platform focused on expense management and integration with partner systems. The role centers on building scalable Kotlin-based microservices, leading design choices, and mentoring teammates while ensuring reliability across distributed cloud environments.

You will collaborate with cross-functional squads, drive performance improvements, and shape the architecture as the team scales in Poland.

Qualifications

• Minimum 5 years of professional software development experience.
• Expertise in server-side Kotlin and distributed systems.
• Experience with cloud environments (AWS) and Kubernetes.
• Proficiency with PostgreSQL, testing frameworks (JUnit, Testcontainers), and observability tools like Grafana.
• Strong problem-solving and mentoring mindset.
• Very good English (min B2) and Poland residency.

Responsibilities

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

Skills

Kotlin

Microservices

Distributed systems

English (B2)

Mentoring teammates

Tools

AWS

Kubernetes

PostgreSQL

Grafana

JUnit

Testcontainers

Job description

Sii Poland is hiring a senior software engineer to join a fintech platform focused on expense management and integration with partner systems. The role centers on building scalable Kotlin-based microservices, leading design choices, and mentoring teammates while ensuring reliability across distributed cloud environments.

You will collaborate with cross-functional squads, drive performance improvements, and shape the architecture as the team scales in Poland.