Kotlin Backend Engineer – Fintech Microservices

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

Benefits offered by this job

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

Job summary

Sii Poland is hiring for a backend-focused role on a modern fintech platform in Kraków. You will design, build, and maintain microservices in Kotlin and collaborate with cross-functional teams across Platform, Services, SMB, and other domains.

You'll work on performance monitoring, reliability, and scalability enhancements, participate in code reviews, and help raise overall code quality and system architecture. English proficiency is required; residency in Poland is mandatory.

Qualifications

• At least 3 years of professional software development experience.
• Hands-on Kotlin in commercial projects required.
• Experience building backend systems and microservices is essential.
• Basic experience with cloud environments (e.g., AWS, Kubernetes).
• Experience with relational databases (PostgreSQL) and with testing/observability tools (JUnit, Grafana).
• Good command of English; resident in Poland is 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 improvements in code quality and system architecture.
• Troubleshoot and resolve technical issues as they arise.

Skills

Kotlin

Backend development

Microservices architecture

Cloud environments

Relational databases

Testing & observability

English

Tools

JUnit

Grafana

PostgreSQL

AWS

Kubernetes

Job description

Sii Poland is hiring for a backend-focused role on a modern fintech platform in Kraków. You will design, build, and maintain microservices in Kotlin and collaborate with cross-functional teams across Platform, Services, SMB, and other domains.

You'll work on performance monitoring, reliability, and scalability enhancements, participate in code reviews, and help raise overall code quality and system architecture. English proficiency is required; residency in Poland is mandatory.