Regular Kotlin Developer (f/m/x)

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

Benefits offered by this job

Great Place to Work

Profit sharing

Centre of internal trainings

Many experts you can learn from

Open and accessible management team

Regular integration events and trips

Comfortable and well-equipped offices

MySii app

Medical care

Job summary

Sii Poland is seeking a Kotlin backend developer to design, build, and maintain microservices for a modern fintech platform in Warsaw. You will collaborate with cross-functional teams across Platform, Services, SMB, and other domains to deliver scalable backend solutions.

The role requires at least 3 years of professional software development experience, with hands-on Kotlin, cloud (AWS/Kubernetes), and PostgreSQL expertise. Excellent English is essential; Poland residency is required.

Qualifications

• 3+ years of professional software development experience.
• Proficient with Kotlin in commercial projects.
• Experience building backend systems with microservices.
• Knowledge of cloud environments (AWS, Kubernetes) preferred.
• Experience with relational DB (PostgreSQL) and testing/observability tools (JUnit, Grafana).
• Strong command of English and residing in Poland required.

Responsibilities

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

Skills

Kotlin

Microservices

Backend development

AWS/Kubernetes

PostgreSQL

JUnit/Grafana

English

Tools

AWS

Kubernetes

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

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