Senior Backend Developer (Python)

We are the Intelligent Internet Platform.

We connect

• People, Places and Things anywhere, managing Internet Performance better than anyone else while providing
• One Global Experience, giving
• Visibility, Control and Security through expereoOne.
• Expereo believes in the power of Internet connectivity. As the world's largest provider of managed internet, SD-WAN/SASE, and Cloud connectivity solutions, we power enterprises and government sites worldwide, helping to enhance every business' productivity with flexible and optimal Internet performance.
• As a trusted partner of Fortune 500 enterprises, our continued aim and success in helping our customers and partners depends solely on the talented individuals who make Expereo a dynamic, effective, multicultural, and equitable environment.

About the role

• We are looking for a Backend Developer to join the Supplier onboarding and Quote Management teams and work directly on the computational core of our platform.
• You will write Python and/or dotnet every day. You will work on an existing Python/C# backend and create new services. You will work on solving real-world business problems, like creating a constraint optimization engine, working on integrations with our partners and creating and maintaining internal tools.
• The core of the role sits at the intersection of three things:
• Algorithmic implementation — translating complex commercial requirements into deterministic, auditable logic. You will implement and maintain the optimization engine that drives our quote generation.
• API design and contract maintenance — defining clear contracts between services, and ensuring the interface is clean, versioned, and reliable for downstream consumers.
• Code quality and engineering discipline — making code production-ready and scalable: writing tests, applying engineering standards, and ensuring the codebase can grow with the platform.
• You will work directly with the innovation and commercial teams.

This role is also designed with growth in mind. The knowledge and context you build here — deep familiarity with the platform, the commercial logic, and the constraints of the business — make this a natural stepping stone toward a technical execution role, potentially supporting a commercial STO (single thread owner) function as the platform scales.

Key Responsibilities

• Business Logic Implementation
• Implement and maintain business logic for the quote engine, partner integrations and internal services: supplier selection, service bundling, routing rules, 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 — we don’t build black boxes.
• Validate model outputs against historical data; measure and report on prediction reliability.
• Optimize the operational value of the integrations with our partners.

API Design & Contract Maintenance

• Define contracts, manage versioning, and ensure downstream consumers are never 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 between components.
• Maintain API documentation as a living artifact, not an afterthought.

Code Quality & Engineering Practices

• Refactor and clean up existing Python/C# code: reduce complexity, increase testability, and bring the codebase up to production engineering standards.
• Write unit and integration tests that provide real confidence — not just coverage numbers.
• Apply Git, code review, and CI practices to all work. Code lives in a repository, goes through review, and is reproducible without intervention.
• Document non-obvious logic thoroughly so knowledge is transferable.

Collaboration & Communication

Partner with the Commercial teams, Quote Engine lead Platform engineer — this is collaborative work, not ticket execution.

Participate in sprint reviews, propose approaches, and flag risks early.

Requirements

• Must-Have
• Advanced Python — non-negotiable. Clean, tested, reusable code. Not just scripts that happen to work.
• API design and implementation. Designing and maintaining REST APIs with clear contracts, versioning, and proper error handling.
• Software engineering discipline. Testing, code review, Git, and the habits of someone who builds things that others can maintain.
• 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.

Strong Plus

• 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.

Benefits

• Part of a team that is engaged and owning the things they do, highly trustable with direct commercial stakes.
• Direct access to production systems, real data, and decision-makers — no layers of process between your work and its impact.
• Exposure to cutting-edge technologies and large-scale global networks.
• A role designed with trajectory in mind — the knowledge you build here is directly applicable to a senior technical execution path.

Competitive compensation

• Pension Plan
• Hybrid Working
• 25 Days Holidays