Java Backend Engineer — Freelance (FinTech Data)

Flix; Województwo mazowieckie; On-site; PLN 242,000 - 545,000; Part time

Job summary

Flix is seeking a skilled Java Engineer to join on a freelance/service agreement basis (B2B). You will work on finance technology, building and maintaining internal applications for revenue accounting, invoices, and partner settlements.

You will design, implement, and operate data-heavy services, collaborate with finance and partner teams, and contribute to CI/CD on AWS, containers with Docker/Kubernetes, and observability with Datadog.

Qualifications

• At least 3 years of experience as a Software Engineer, with exposure to data processing systems.
• Proven experience working with Java in a commercial environment
• Experience with event-driven architectures, ideally Kafka
• Experience working with cloud-based infrastructure providers, ideally AWS
• Solid SQL knowledge
• Hands‑on experience with Docker and Kubernetes (or similar container orchestration tools) and CI/CD
• Familiarity with Snowflake or similar data warehousing solutions is a plus

Responsibilities

• Design, build, and maintain features for the internal data-heavy applications, supporting automated bus partner settlement generation across all FlixBus entities around the globe.
• Develop and enhance the internal services that allow finance and billing teams to manage bus partners' settlement-relevant data and track changes via event history.
• Communicate directly with business counterparts (finance, billing, and partner teams) to understand needs and shape solutions.
• Actively participate in product development, from refinement and technical design through delivery and operations.
• Implement and maintain event-driven data processing workflows using Kafka to support settlement operations.
• Contribute to infrastructure-as-code practices and CI/CD pipelines on AWS, and run services on Docker/Kubernetes, with monitoring and observability (e.g. Datadog).

Skills

Java programming

Data processing systems

SQL

Tools

Kafka

AWS

Docker

Kubernetes

Snowflake

Job description

Flix is seeking a skilled Java Engineer to join on a freelance/service agreement basis (B2B). You will work on finance technology, building and maintaining internal applications for revenue accounting, invoices, and partner settlements.

You will design, implement, and operate data-heavy services, collaborate with finance and partner teams, and contribute to CI/CD on AWS, containers with Docker/Kubernetes, and observability with Datadog.