Python API Developer

Function

We're looking for a Senior Python API Developer to join our client's team on a challenging technical consulting assignment. You'll play a key role in building a secure, production-ready API solution that will enable users to transition away from an existing third-party interface with minimal disruption. This is an opportunity for an experienced engineer who enjoys working with existing systems, making pragmatic technical decisions, and delivering high-quality solutions from sometimes incomplete documentation.

Role & Responsibilities

You'll take ownership of analysing the existing API, defining the most valuable functionality to reproduce, and implementing a clean, maintainable solution aligned with an existing PostgreSQL database and data-loading processes. Your responsibilities will include:

• Analyse the existing API and documentation and define the implementation scope.

• Review the existing database schema and map its metadata to the API model.

• Identify and document functional gaps between the existing interface and the new solution.

• Design and implement REST API endpoints using Python 3.12+ and FastAPI.

• Build metadata endpoints on top of an existing PostgreSQL database using SQLAlchemy.

• Develop submission endpoints with robust validation and meaningful error handling.

• Integrate submitted data with an existing Python-based loading process or store it in the required format.

• Design and implement appropriate approaches for authentication, authorization, transport security, and secure data handling.

• Develop comprehensive automated tests using pytest.

• Produce concise technical documentation and clearly communicate limitations, risks, open questions, and recommended next steps.

• Deploy and demonstrate the solution on Ubuntu Linux.

Technical Profile

We're looking for a hands-on senior developer with strong experience in Python API development, REST services, and database-driven integrations. You should be comfortable understanding existing schemas, working independently, and delivering tested, production-quality code.

Essential skills:

• Strong Python 3.12+ development experience, particularly with FastAPI.

• Solid knowledge of SQLAlchemy and PostgreSQL, including working with and mapping existing database schemas.

• Strong understanding of REST API design and implementation.

• Practical knowledge of API security, including OAuth2/OIDC, JWT, API keys, TLS, authentication, authorization, and input validation.

• Experience writing automated tests with pytest.

• Ability to work autonomously with incomplete or imperfect documentation.

• Pragmatic approach focused on critical scope, delivery, quality, and maintainability.

• Strong communication skills, particularly when explaining technical findings, risks, limitations, and trade-offs.

Nice to have:

• Experience with Polars and SQLAlchemy.

• Familiarity with uv for Python package management.

• Previous experience with API compatibility, replacement, or migration projects.

• Experience handling sensitive data and working with GDPR-related requirements.

• Linux deployment experience.

• Exposure to both REST and SOAP environments.

Assignment Details

This is a technical consulting assignment requiring production-quality code, automated testing, clear documentation, and a working deployment/demo environment. The ability to work independently and make sound technical decisions will be particularly important. Dutch, English, and French language skills are relevant for the assignment.

Contactperson & Reference

• Reference #: INW28304
• Pieter Messely
• pieter.messely@i4m.be