Senior Backend Developer (Python)

Join our team as a Senior Backend Developer, where you will work on the computational core of our platform. You will write Python and/or C# daily, create new services, and solve real-world business problems. This role offers growth opportunities and the chance to work directly with the innovation and commercial teams.

• Implement and maintain business logic for the quote engine, partner integrations, and internal services, ensuring all outputs are auditable and explainable to commercial stakeholders.
• Write clear, well-documented API interfaces with explicit input/output contracts and error handling, and maintain API documentation as a living artifact.
• Refactor and clean up existing Python/C# code to reduce complexity, increase testability, and bring the codebase up to production engineering standards.
• Ability to work in a mixed-language codebase. The existing platform is Python/C#. You need to be comfortable reading it and understanding the integration points
• Advanced Python — non-negotiable. Clean, tested, reusable code. Not just scripts that happen to work
• Software engineering discipline. Testing, code review, Git, and the habits of someone who builds things that others can maintain
• API design and implementation. Designing and maintaining REST APIs with clear contracts, versioning, and proper error handling
• C#: You will also work with the existing platform, you need to write quality, clean, testable code in C#
• Familiarity with AWS services (Lambda, API Gateway, S3) or equivalent cloud infrastructure
• Experience with API specification tooling (OpenAPI/Swagger, Pydantic, etc.)
• Exposure to Python packaging, dependency management, and CI pipelines
• Familiarity with constraint-solving tools such as OR-Tools, PuLP, or equivalent in a real-world setting
• Experience in a B2B SaaS, telecom, or logistics context where algorithmic correctness has real commercial stakes
• Comfort with performance profiling and optimization in Python