Senior Backend Developer (Python)

Expereo is a Manage Network as a Services company that connects people, places and things anywhere. They empower global companies to be future-ready by delivering secure, global network connectivity to enterprise and government sites in over 190 countries. Their offices are located worldwide including the Netherlands, the United Kingdom, Poland, United States, Singapore, Philippines, United Arab Emirates, Argentina, Brazil, and Spain.

Must-Have:

• Advanced Python skills with clean, tested, reusable code.
• Experience in API design and implementation including REST APIs with clear contracts, versioning, and error handling.
• Software engineering discipline including testing, code review, and Git.
• Ability to work in a mixed-language codebase (Python/C#).

Strong Plus:

• Proficiency in C# with quality, clean, testable code.
• Familiarity with AWS services such as Lambda, API Gateway, and S3 or equivalent cloud infrastructure.
• Experience with API specification tooling like OpenAPI/Swagger and Pydantic.
• Exposure to Python packaging, dependency management, and CI pipelines.
• Familiarity with constraint-solving tools such as OR-Tools or PuLP.
• Experience in B2B SaaS, telecom, or logistics contexts with algorithmic correctness.
• Comfort with performance profiling and optimization in Python.

Business Logic Implementation:

• Implement and maintain business logic for the quote engine, partner integrations and internal services including supplier selection, service bundling, routing rules, and product validation.
• Explore, document and integrate heterogeneous external data sources necessary to the execution of business logic.
• Ensure all outputs are auditable and explainable to commercial stakeholders.
• Validate model outputs against historical data and measure prediction reliability.
• Optimize the operational value of integrations with partners.

API Design & Contract Maintenance:

• Define contracts, manage versioning, and ensure downstream consumers are not broken silently.
• Write clear, well-documented API interfaces with explicit input/output contracts and error handling.
• Coordinate with the Platform engineer on service integration and ensure clean separation of concerns.
• Maintain API documentation as a living artifact.

Code Quality & Engineering Practices:

• Refactor and clean up existing Python/C# code to reduce complexity and increase testability.
• Write unit and integration tests that provide real confidence.
• Apply Git, code review, and CI practices to all work.
• Document non-obvious logic thoroughly for knowledge transfer.

Collaboration & Communication:

• Partner with Commercial teams, Quote Engine lead, and Platform engineer.
• Participate in sprint reviews, propose approaches, and flag risks early.