Kotlin Backend Developer – Fintech Microservices

Sii Poland; Województwo pomorskie; On-site; PLN 120,000 - 210,000; 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 backend engineer to design, build, and maintain Kotlin-based microservices within a fintech platform for expense management. You will collaborate with cross-functional teams across Platform, Services, SMB, and other domains to deliver scalable solutions.

Ideal candidates have 3+ years in software development, Kotlin in commercial projects, and experience with backend systems, cloud environments, PostgreSQL, and observability tools.

Qualifications

• 3+ years of professional software development experience.
• Hands-on Kotlin experience in commercial projects.
• Experience building backend systems and microservices.
• Basic familiarity with cloud environments (AWS, Kubernetes).
• Experience with PostgreSQL and testing/observability tools (JUnit, Grafana).
• Good command of English; residence in Poland preferred.

Responsibilities

• Designing, building, and maintaining microservices using Kotlin.
• Collaborating with cross-functional teams to deliver solutions across Platform, Services, SMB, and other domains.
• Supporting system performance monitoring and improving reliability and scalability.
• Participating in code reviews and maintaining high code quality.
• Contributing to continuous improvement of code quality and system architecture.
• Troubleshooting and resolving technical issues.

Skills

Kotlin

Microservices architecture

Backend development

Cloud environments (AWS, Kubernetes)

Relational databases PostgreSQL

Testing/Observability (JUnit, Grafana)

English language

Tools

AWS

Kubernetes

PostgreSQL

JUnit

Grafana

Job description

Sii Poland is hiring a senior backend engineer to design, build, and maintain Kotlin-based microservices within a fintech platform for expense management. You will collaborate with cross-functional teams across Platform, Services, SMB, and other domains to deliver scalable solutions.

Ideal candidates have 3+ years in software development, Kotlin in commercial projects, and experience with backend systems, cloud environments, PostgreSQL, and observability tools.