Lead Kotlin Engineer - Fintech Microservices on AWS

Sii Sp. z o.o.; Rzeszów; On-site; PLN 180,000 - 230,000; Full time

Job summary

Sii Sp. z o.o. in Rzeszów is seeking a Kotlin Developer to join a fintech-focused team building scalable microservices and cloud-native platforms.

You will design, implement, and maintain services primarily in Kotlin, collaborate with cross-functional teams across Platform, Services, SMB, and related domains, and mentor peers to boost code quality and reliability. The role demands strong English, at least 5 years of professional software development experience, and practical knowledge of AWS,

Qualifications

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

Responsibilities

• Leading initiatives to design, build, and maintain scalable microservices primarily using Kotlin
• Collaborating with cross-functional teams to develop solutions across Platform, Services, SMB, and other domains
• Analyzing system performance and implementing optimizations for reliability and scalability
• Participating in code reviews, post-mortems, and mentoring engineers
• Proactively improving architecture and leading migrations

Skills

Kotlin

AWS

Microservices

Kubernetes

Tools

PostgreSQL

JUnit

Testcontainers

Grafana

React.js

TypeScript

Job description

Sii Sp. z o.o. in Rzeszów is seeking a Kotlin Developer to join a fintech-focused team building scalable microservices and cloud-native platforms.

You will design, implement, and maintain services primarily in Kotlin, collaborate with cross-functional teams across Platform, Services, SMB, and related domains, and mentor peers to boost code quality and reliability. The role demands strong English, at least 5 years of professional software development experience, and practical knowledge of AWS,