Senior Kotlin Backend Engineer – Fintech Microservices

Sii Poland; Województwo kujawsko-pomorskie; On-site; PLN 180,000 - 240,000; Full time

Benefits offered by this job

Great Place to Work

Solid financial situation

Contracts with big brands

Centre of internal trainings

Many experts you can learn from

Open management team

Profit sharing

MySii app

Job summary

Sii Poland is hiring a senior software engineer to shape and grow a fintech platform focused on expense and financial tooling. You will design and implement scalable microservices in Kotlin, collaborate across Platform, Services, and SMB domains, and mentor teammates while driving architectural improvements.

Ideal candidates bring 5+ years in software development, strong Kotlin and cloud experience (AWS, Kubernetes), PostgreSQL expertise, and solid English communication.

Qualifications

• 5+ years of professional software development experience.
• Strong Kotlin backend skills and distributed systems experience.
• Experience with cloud environments (AWS) and Kubernetes.
• Proficiency with PostgreSQL and modern testing frameworks.

Responsibilities

• Lead design, build, and maintenance of scalable microservices using Kotlin.
• Collaborate with cross-functional teams across Platform, Services, SMB, and domains.
• Analyze performance and implement reliability and scalability optimizations.
• Participate in code reviews, post-mortems, and mentor engineers.
• Drive architectural improvements and migrations.

Skills

Kotlin backend

Microservices architecture

Cloud environments

PostgreSQL

Testing (JUnit/Testcontainers)

Observability (Grafana)

English (B2+)

Tools

PostgreSQL

JUnit

Testcontainers

Grafana

AWS

Kubernetes

Job description

Sii Poland is hiring a senior software engineer to shape and grow a fintech platform focused on expense and financial tooling. You will design and implement scalable microservices in Kotlin, collaborate across Platform, Services, and SMB domains, and mentor teammates while driving architectural improvements.

Ideal candidates bring 5+ years in software development, strong Kotlin and cloud experience (AWS, Kubernetes), PostgreSQL expertise, and solid English communication.