Regular Kotlin Developer (f/m/x)

Sii Sp. z o.o.; Warszawa; On-site; PLN 180,000 - 280,000; Full time

Benefits offered by this job

Private healthcare

Remote work

Profit sharing

Training platform

Tech blog

Career growth

Job summary

Sii Sp. z o.o. in Warsaw is seeking a Regular Kotlin Developer to design, build, and maintain Kotlin-based microservices within a fintech-oriented platform.

You will collaborate with cross-functional teams to deliver scalable backend solutions and help ensure performance and reliability across services. Ideal candidates have at least 3 years in software development, strong Kotlin experience, and familiarity with cloud services like AWS and Kubernetes.

Qualifications

• Minimum 3 years of professional software development experience.
• Hands-on Kotlin experience in commercial projects.
• Experience building backend systems and working with microservices architecture.
• Basic experience with cloud environments (AWS, Kubernetes).
• Experience with relational databases (PostgreSQL) and testing/observability tools (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 reliability and scalability improvements.
• Participating in code reviews and maintaining high code quality standards.
• Contributing to continuous improvement of code quality and system architecture.
• Troubleshooting and resolving technical issues.

Skills

Kotlin

AWS

Kubernetes

Microservices

PostgreSQL

JUnit 5

Job description

Regular Kotlin Developer (f/m/x)

Miejsce pracy: Warszawa

Technologies we use

Expected

• Kotlin
• AWS
• Kubernetes
• Microservices
• PostgreSQL
• JUnit 5

About the project

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 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

Our 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

What we offer

• Great Place to Work since 2015 - it’s thanks to feedback from our workers that we get this special title and constantly implement new ideas
• Employment stability - revenue of PLN 2.1BN, no debts, since 2006 on the market
• We share the profit with Workers - over PLN 76M has already been allocated for this aim since 2022
• Attractive benefits package - private healthcare, benefits cafeteria platform, car discounts and more
• Comfortable workplace – class A offices or remote work
• Dozens of fascinating projects for prestigious brands from all over the world – you can change them thanks to Job Changer application
• PLN 1 000 000 per year for your ideas - with this amount, we support the passions and voluntary actions of our workers
• Investment in your growth – meetups, webinars, training platform and technology blog – you choose
• Fantastic atmosphere created by all Sii Power People

Sii Sp. z o.o.

Sii is the leading technology consulting, digital transformation, engineering, and business services vendor in Poland. We already employ more than 7 300 professionals and implement projects in a variety of industries for clients from many countries around the world. The Great Place to Work title, won 10 times in a row, proves that at Sii, we create a friendly work environment.

Sii ensures that all employment-related decisions are made solely on the basis of qualifications and competencies. We are committed to equal treatment of all individuals, regardless of any protected characteristics, and promoting a diverse and inclusive work environment.