Java/Kotlin Software Engineer — AI & DS (Contract)

Flix; Warszawa; Remote; PLN 180,000 - 300,000; Full time

Job summary

Flix is seeking an experienced Software Engineer to join on a freelance/service agreement basis (B2B). You will work on a critical product central to the Flix ecosystem, coordinating with Mobility Partners to keep millions of passengers moving globally.

You’ll contribute to architecture, scale the product, and explore AI-driven solutions while collaborating with a distributed team in an Agile environment. This role emphasizes ownership, high-quality code, and user-focused outcomes.

Qualifications

• 6+ years of experience as a Software Java and/or Kotlin Engineer, with knowledge of distributed systems, including Spring/Spring Boot, Kafka, MySQL/Postgres, Redis, MongoDB and S3
• Willingness to work with both Java (for existing products) and Kotlin (for new ones)
• Experience in making architectural decisions, and writing clean, performant, well-tested code
• Autonomy and ownership in solving technical challenges, as well as strong communication skills when working with a distributed team
• A strong product mindset, with a passion for user experience and a data-driven approach to decision-making
• Experience in coding with AI
• Fluent in English (upper-intermediate or higher)

Responsibilities

• Collaborate with a distributed, self-organized, cross-functional team
• Co-design new products from the ground up while continuously improving existing ones, with room to explore and implement cutting-edge technologies
• Drive the development process in an Agile environment, placing Flix users at the center of each solution you and the team create
• Support technical decisions across teams, improving technical excellence through collaboration and lateral leadership
• Help define and deliver products that optimize the coordination between Flix and Mobility Partners, enhancing efficiency and reducing manual tasks

Skills

Java

Kotlin

Distributed systems

Spring Boot

Kafka

MySQL/Postgres

Redis

MongoDB

S3

Fluent English

English

Tools

Kubernetes

Docker

GitLab CI

AWS

Terraform

Snowflake

Job description

Flix is seeking an experienced Software Engineer to join on a freelance/service agreement basis (B2B). You will work on a critical product central to the Flix ecosystem, coordinating with Mobility Partners to keep millions of passengers moving globally.

You’ll contribute to architecture, scale the product, and explore AI-driven solutions while collaborating with a distributed team in an Agile environment. This role emphasizes ownership, high-quality code, and user-focused outcomes.