Regular Kotlin Developer (f/m/x)

Sii Poland; Toruń; On-site; PLN 180,000 - 240,000; Full time

Benefits offered by this job

Centre of internal trainings

Profit sharing

Medical care

Regular integration events and trips

Great Place to Work

Job summary

Sii Poland is seeking a backend engineer to join a fintech platform that streamlines company expense management. The role focuses on designing, building and maintaining Kotlin-based microservices integrated into partner systems and cloud environments.

You will collaborate with cross‑functional teams across multiple domains, contribute to performance monitoring, reliability and scalability, and participate in code reviews to uphold high quality standards.

Qualifications

• Minimum 3 years of professional software development experience.
• Hands-on Kotlin experience in commercial projects.
• Experience building backend systems and microservices architecture.
• Basic experience with cloud environments (e.g., AWS, Kubernetes).
• Experience with relational databases (e.g., PostgreSQL) as well as testing and observability tools (e.g., JUnit, Grafana).
• Good command of English.
• Residing in Poland required.

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 contributing to improvements in reliability and scalability.
• Participating in code reviews and maintaining high code quality standards.
• Contributing to the continuous improvement of code quality and system architecture.
• Troubleshooting and resolving technical issues.

Skills

Kotlin

Microservices

Backend systems

Cloud (AWS/Kubernetes)

PostgreSQL

Testing & observability (JUnit, Graf S

English

Tools

Kubernetes

Job description

Join a team working on a modern fintech platform that supports company expense management.

The project focuses on developing a finance solution that enables seamless integration of financial tools (including payment cards, expense management, and invoice handling) directly into partner systems such as banks, accounting platforms, and HR solutions. The product allows companies to simplify financial processes, automate settlements, and gain full real-time control over their spending.

Your tasks

• 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 contributing to improvements in reliability and scalability
• Participating in code reviews and maintaining high code quality standards
• Contributing to the continuous improvement of code quality and system architecture
• Troubleshooting and resolving technical issues

Requirements

• Minimum 3 years of professional experience in software development
• Hands‑on experience with Kotlin in commercial projects
• Experience building backend systems and working with microservices architecture
• Basic experience with cloud environments (e.g., AWS, Kubernetes)
• Experience with relational databases (e.g., PostgreSQL) as well as testing and observability tools (e.g., JUnit, Grafana)
• Good command of English
• Residing in Poland required

Job no. JOB-9KXRB

Sii ensures that all hiring decisions are made solely on the basis of qualifications and competence. We are committed to equal and fair treatment of all, regardless of legally protected characteristics. At Sii, we promote a diverse and inclusive work environment, in full compliance with applicable anti-discrimination laws.

Benefits For You

• 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