Kotlin Developer (f/m/x)

Sii Sp. z o.o.; Kraków; On-site; PLN 120,000 - 180,000; Full time

Benefits offered by this job

Great Place to Work

Private healthcare

Remote work option

Profit sharing

Job summary

Sii Sp. z o.o. in Kraków is seeking a Kotlin Developer (f/m/x) to design, implement and maintain scalable microservices using Kotlin, AWS, and cloud-native patterns.

You will collaborate with cross-functional teams across Platform, Services, and SMB to deliver robust fintech solutions and integrations with banks, accounting platforms, and HR tools. The role emphasizes mentoring, code reviews, and performance tuning to ensure reliability and scalability, with English proficiency and 5+ years of

Qualifications

• 5+ years of professional software development experience.
• Expertise in server-side languages, especially Kotlin, and distributed systems/microservices.
• Experience with cloud environments (AWS) and Kubernetes.
• Proficiency with PostgreSQL, testing tools (JUnit, Testcontainers), and observability (Grafana).
• Strong problem solving and collaboration; able to mentor teammates.

Responsibilities

• Lead design, build, and maintenance of scalable microservices using Kotlin.
• Collaborate with cross-functional teams across Platform, Services, SMB, and others.
• Analyze performance and implement optimizations for reliability and scalability.
• Participate in code reviews, post-mortems, and mentor engineers.
• Drive architectural improvements and migrations.

Skills

Kotlin

AWS

Microservices

Kubernetes

Tools

React.js

TypeScript

Job description

Kotlin Developer (f/m/x)

Miejsce pracy: Kraków

Technologies we use

Expected

• Kotlin
• AWS
• Microservices
• Kubernetes

Optional

• React.js
• TypeScript

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 being developed allows companies to simplify financial processes, automate settlements, and gain full real-time control over their spending.

Your responsibilities

• Leading initiatives to design, build, and maintain scalable microservices primarily using Kotlin
• Collaborating with cross-functional teams to develop innovative solutions across Platform, Services, SMB, and other domains
• Analyzing system performance and implementing optimizations to ensure high reliability and scalability
• Participating in code reviews, post-mortems, and providing mentorship to other engineers
• Proactively improving the architecture and quality of solutions, and leading the team through technical challenges and migrations

Our requirements

• Minimum 5 years of professional experience in software development
• Expertise in server-side languages, especially Kotlin, and experience with distributed systems, microservices, and cloud environments (e.g., AWS, Kubernetes)
• Proficiency with relational databases like PostgreSQL, testing frameworks (e.g., JUnit, Testcontainers), and observability tools like Grafana
• Strong problem-solving skills and a collaborative mindset to mentor and upskill your teammates
• Very good knowledge of English - min. B2 level
• Residing in Poland required

Optional

• Previous work in the fintech industry or with financial products
• Knowledge of topics related to payments, cards, or accounting
• Experience working in a scale-up environment
• Proficiency in one of the following front-end technologies: React or TypeScript

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.