Senior Java Engineer - Flix Train Operations Management System

Flix is hiring a Senior Java Engineer - Flix Train Operations Management System in Warsaw, Poland. Level rates it ; you can apply on Flix.

Level's read on this job

Level rates this role Little AI ●○○○: aI is not part of the work.
The posting mentions Java, Spring Boot and Kafka among its tools and skills.
Level classes it as a senior role.
Flix has 165 other open roles on Level.
Posted in the last few days.

AI in this role

Design and develop distributed backend systems and internal tools for FlixTrain operations using Java and AWS.

JavaSpring BootKafkaMySQLMongoDBAWSDockerKubernetesTerraformDatadogRedisGitLab Ci

89-119 PLN/hour

We are looking for a skilled Senior Java Engineer for service agreement collaboration (B2B contract) to cooperate with a team that focuses on automating and streamlining FlixTrain’s operational processes, creating internal tools that help teams manage a growing and increasingly modern fleet. The team works in a collaborative, pragmatic, low-bureaucracy way.

Scope of services

This engagement sits in a greenfield environment, where many systems are designed and built from scratch. Engineers are actively involved throughout the entire lifecycle: understanding operational challenges, contributing to architectural decisions, and ensuring high quality through solid testing practices. We value engineers who are curious about the business, eager to participate in discovery and problem framing, and comfortable navigating ambiguity.

About the Engagement

Collaborate with a self-organized, cross-functional distributed team responsible for a set of products, contributing directly to the success of the business
Place our users at the center when developing solutions together with the team
Contribute to the development process within an Agile environment
Design new products from scratch and frequently deliver new versions of existing products, using continuous integration and automation
Work with cutting-edge technologies and tools
Contribute to technical decisions inside and across teams to improve technical excellence
Share knowledge and provide technical guidance through code reviews and close collaboration
Our tech stack: Java, Spring/Spring Boot, Kafka, MySQL (RDS), MongoDB (DocumentDB), AWS, Docker, GitLab CI, Kubernetes, Terraform, Datadog

About You

7+ years of professional experience with Java
Strong experience developing distributed systems using Spring Boot
Experience with relational (MySQL, PostgreSQL, RDS) and NoSQL databases (MongoDB, DocumentDB)
Experience with caching solutions such as Redis, ElastiСache
Experience with event-driven architectures and messaging services like Kafka/SQS/SNS/RabbitMQ
Hands-on experience with AWS services (e.g. RDS, S3, EC2)
Experience with DevOps and infrastructure technologies, including Docker, Kubernetes, GitLab CI, Terraform, and Datadog
Upper-intermediate level of English or higher
Experience working within an Agile setup

Nice to have:

Data Engineering skills: ETL, Snowflake, etc.
Experience working with distributed teams

Collaboration model

Contract type: Cooperation based on a service agreement (B2B/freelance contract), not an employment contract
Working model: Independent contractor responsible for delivering agreed services and submitting invoices

How we rate this

Senior Java Engineer - Flix Train Operations Management System at Flix rates 0 out of 100 for how much of the daily work is AI. That makes it Little AI (AI Level 1 of 4). The level is about AI in the job, not seniority.

Classification

Little AI. AI is not part of the work.

●●●● Builds AI80 to 100
●●●○ Works on AI60 to 79
●●○○ Uses AI40 to 59
●○○○ Little AI0 to 39

Levels come from how often the tools, models and workflows of the role are named in the posting itself. Read the description and count the AI tools, models and workflows it names.

Key facts

Senior Java Engineer - Flix Train Operations Management System is an open job at Flix.
Level rates this role AI Level 1 of 4: Little AI.
The role is based in Warsaw.
The job was posted on November 10, 2026.
Seniority: senior.
Applications are handled by Flix. Apply on Flix

Prepare for this job

Built from this posting and from similar jobs on Level.

Skills and AI tools this role asks for

JavaSpring BootKafkaMySQLMongoDBAWSDockerKubernetes

Questions you could be asked

What's a project where you used Java hands-on?
Walk me through how you've used Spring Boot in your day-to-day work.
What are the limits of Kafka that you've run into, and how did you work around them?
What's a project where you used MySQL hands-on?
Walk me through how you've used MongoDB in your day-to-day work.

Adapt your resume

List these exact terms on your resume: Java, Spring Boot, Kafka, MySQL, and MongoDB. An applicant tracking system matches the wording, not the idea.
Attach one line of real, concrete experience to at least one of them. A tool named with nothing behind it rarely survives a human read.

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