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# API Developer

- **Company:** Keystone Solutions
- **Location:** Brussel, Belgium
- **Contract:** Temporary contract
- **Skills:** Application Programming Interfaces (APIs), Automation of Tests, Ubuntu (Operating System), Databases, Data Validation, Linux, Python (Programming Language), PostgreSQL, OAuth, OpenID, Package Management Systems, JSON Web Token, Simple Object Access Protocol (SOAP), SQLAlchemy, WS-Security, Software Security, Fastapi, Pytest, Api Design, Restful APIs
- **Published:** October 6, 2026
- **Apply:** https://www.indeed.com/viewjob?jk=6fc0995e7d4ef4a3

## About the Role

* Python 3.12+ with FastAPI.
 * SQLAlchemy and PostgreSQL (reading and mapping an existing schema).
 * REST API design.
 * API security: authentication and authorization (e.g. OAuth2/OIDC, JWT, API keys), TLS, input validation.
 * Automated testing (pytest).

Nice to Have:

 * Polars in combination with SQLAlchemy.
 * uv for package management.
 * Experience with API compatibility or migration projects.
 * Experience handling sensitive data (e.g. health data) and GDPR requirements.
 * Linux deployment experience.

Soft Skills:

 * Autonomy and ability to work from incomplete documentation.
 * Pragmatism: focusing on the critical parts first while keeping quality high on what is delivered.
 * Clear communication of findings and limitations.

At Keystone Solutions, we pride ourselves on our consultancy nature, offering dynamic projects that provide turbo-charged learning opportunities. As a

If you are ready to tackle technical and strategic challenges in a dynamic consultancy environment, apply today ., * API - Level: Expert - Most recent: Any time

 * API Design - Level: Expert - Most recent: Any time
 * API Developer experience (SOAP en REST) - Level: Expert - Most recent: Any time
 * API development (FastAPI,...) - Level: Expert - Most recent: Any time
 * API Security a.d.h.v. OAuth en WS-Security - Level: Expert - Most recent: Any time
 * PostgreSQL - Level: Expert - Most recent: Any time
 * Pytest - Level: Expert - Most recent: Any time
 * Python - Level: Expert - Most recent: Any time
 * REST - Level: Expert - Most recent: Any time
 * SQLAlchemy - Level: Expert - Most recent: Any time

## Description

* Analyze the existing API and its documentation, and agree on the subset to cover.
 * Analyze the ODS database and map its metadata to what the existing API exposes, identifying any gaps.
 * Propose and implement a security approach (authentication, authorization, secure handling of submitted data), highlighting where it differs from the current API.
 * Implement the metadata endpoints on top of the ODS database.
 * Implement the submission endpoints, with validation of submitted data and meaningful error responses.
 * Hand over submitted data to the ODS loading code (or store it in the form that code expects).
 * Write automated tests and concise technical documentation.
 * Deploy and demonstrate the solution on Ubuntu Linux.
 * Report on limitations, open questions, and recommended next steps.