Regular Kotlin Developer (f/m/x)

Sii Poland; Lublin; On-site; PLN 180,000 - 300,000; Full time

Benefits offered by this job

Profit sharing

Medical care

Centre of internal trainings

Regular integration events and trips

Open management team

Job summary

Sii Poland is hiring a Kotlin backend developer to design, build, and maintain microservices for a modern fintech platform. The role involves collaborating with cross-functional teams across Platform, Services, SMB, and other domains to deliver robust solutions and improve system reliability.

The ideal candidate has at least 3 years of experience in software development, hands-on Kotlin in commercial projects, and familiarity with cloud environments and databases.

Qualifications

• Minimum 3 years of professional software development experience.
• Hands-on Kotlin experience in commercial projects.
• Experience building backend systems and microservices architecture.
• Cloud exposure (AWS, Kubernetes).
• Relational databases (PostgreSQL) and testing/observability tools (JUnit, Grafana).
• Good command of English; residing in Poland is required.

Responsibilities

• Design, build, and maintain Kotlin-based microservices.
• Collaborate with cross-functional teams across Platform, Services, SMB, and other domains.
• Support performance monitoring and contribute to reliability and scalability improvements.
• Participate in code reviews and maintain high code quality.
• Contribute to continual code quality and system architecture improvements.
• Troubleshoot and resolve technical issues.

Skills

Kotlin

Backend development

Microservices architecture

Cloud environments (AWS/Kubernetes)

PostgreSQL

Testing/Observability (JUnit, Grafana)

English proficiency

Tools

Kubernetes

AWS

PostgreSQL

JUnit

Grafana

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

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