Java Software Engineer - FinTech

Flix; Województwo mazowieckie; On-site; PLN 123,000 - 164,000; Full time

Job summary

Flix is seeking a Java Engineer to join its freelance service team in Poland. You will design, build, and maintain internal data-heavy applications supporting revenue and settlements, with a focus on correctness and performance.

You will work on event-driven processing with Kafka, integrate with AWS, and contribute to CI/CD pipelines. Collaboration with finance and business teams is essential, and you will operate as an independent contractor under a B2B contract.

Qualifications

• 3+ years of professional software engineering experience.
• Proven Java backend development experience.
• Experience with event-driven architectures, Kafka.
• Experience with cloud infrastructure, ideally AWS.
• Strong SQL knowledge.
• Docker and Kubernetes experience; CI/CD.
• English fluency.

Responsibilities

• Design, build, and maintain internal data-heavy applications for finance and billing.
• Support settlement generation and data reconciliation.
• Collaborate with finance partners to understand needs.
• Contribute to CI/CD pipelines and IaC on AWS.
• Operate with Docker/Kubernetes and observability (Datadog).

Skills

Java

Kafka

AWS

SQL

Docker

Kubernetes

CI/CD

English

Tools

Snowflake

Datadog

Job description

Rate: 89 – 119 / hour (B2B) We are looking for a skilled Java Engineer to join Flix on a freelance/service agreement basis (B2B contract). This is a contractor engagement to work on impactful, hands-on challenges in the domain of financial technology.

Rate: 89 – 119 / hour (B2B) We are looking for a skilled Java Engineer to join Flix on a freelance/service agreement basis (B2B contract). This is a contractor engagement to work on impactful, hands-on challenges in the domain of financial technology.

Scope of Services

Bring expertise in Java-based backend development. Work across Flix's finance technology environment to build and maintain critical internal applications — from revenue accounting, invoices processing to bus partner settlements and payment reconciliation.

About The Engagement

• 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).

About You

• 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
• Experience in front-end technologies (e.g., JavaScript, HTML5, React.js, or Angular) is a plus
• Fluent in English

Cooperation model

• Cooperation based on a service agreement (B2B/freelance contract), not an employment contract.
• You will operate as an independent contractor, responsible for delivering agreed services and submitting invoices
• Location: open for contractors based in Poland