Senior Full-stack Python Engineer; m​/f​/d; Network Planning

At Flix, we offer a tech-driven environment where innovation meets real-world impact, with competitive pay, strong growth opportunities, and a culture of collaboration and ownership.

We're looking for an experienced Senior Full-stack Python Engineer (m/f/d) to join our Supply Division. You'll make an impact by taking ownership of core backend systems that power our network planning optimization product. Your work will directly support network planners in scheduling vehicles, drivers, and timetables — improving travel experiences for millions of passengers while driving profitability.

Our team builds and maintains an optimization platform addressing use cases from vehicle and driver scheduling to timetable optimization. We follow modern system design — Domain-Driven Design, Hexagonal Architecture, and SOLID principles — with strict architectural boundaries enforced by tooling. Our backend workloads (APIs, event consumers, Kubernetes jobs) are built to scale with high code quality standards.

The product's algorithm engine is developed by Operations Research Engineers using mathematical optimization. As a Senior Python Engineer, you will own the engineering shell around these algorithms: the APIs, use cases, data pipelines, infrastructure, and the domain models that connect optimization output to the rest of the system.

You'll collaborate closely with other engineering teams to design and implement the interfaces and contracts that connect our platform to the wider system landscape.

We're building AI into the product itself — combining LLMs with our optimization engine to solve planning problems in new ways.

• Python, Type Script, Shell scripting
• Flask, React, Pytest
• PostgreSQL, Confluent Kafka, Data Dog
• AWS tools, Terraform
• Git Lab, Kubernetes, Docker, Azure AD

• Own and evolve the backend: APIs, use case layer, domain models, serialization, and event-driven pipelines (Kafka)
• Take engineering ownership of new product modules — designing the architectural scaffold, wiring layers, and ensuring clean boundaries
• Build and maintain infrastructure:
  Kubernetes deployments, CI/CD pipelines, and cloud resources (AWS)
• Collaborate closely with Operations Research Engineers to integrate optimization algorithms into the product
  
  Build AI capabilities into the product by combining LLMs with our optimization engine
• Work in an AI-augmented development workflow — actively using code agents and AI assistants as a natural part of how you ship software
• Contribute to architecture decisions and uphold code quality through reviews, testing, and continuous improvement
• Write well-tested, self-documenting code following hexagonal architecture patterns
• Share your expertise and mentor colleagues, promoting a culture of knowledge sharing and learning

• Academic background in Computer Science or equivalent
• 5+ years of experience in backend software engineering with Python
• Experience with modern front-end stack (some basic front-end tasks are part of our scope)
• Experience applying clean architecture principles (hexagonal, ports-and-adapters, DDD) or similar approaches in production — able to contribute from day one
• Experience with relational databases (PostgreSQL) and event-driven systems (Kafka or similar)
• Strong experience in AI-augmented development — actively using code agents or AI assistants in daily work
• Solid experience with containerization (Docker, Kubernetes) and CI/CD pipelines
• Familiar with testing best practices: unit, integration, acceptance testing
• Experience with cloud platforms (AWS or similar) and infrastructure as code (Terraform)
• Familiarity with mathematical optimization or data-intensive applications is a plus

• Travel perks : 12 free Flix vouchers +…