Senior Python (FastAPI) backend developer - Freelance

Taux journalier (TJM): 600

We’re supporting a fast-growing French scale-up operating several SaaS products and a B2B marketplace, with strong technical challenges around scalability, reliability and performance in an international context.

Mission – Key Responsibilities (Tech-focused)

• Design, develop and optimize backend services in Python (FastAPI, Django or Flask).

• Contribute to a progressive migration towards a resilient microservices architecture.

• Build and maintain high-performance, secure REST/GraphQL APIs.

• Improve latency, throughput and fault tolerance of existing services.

• Work on data consistency and transactional flows in a distributed environment.

• Help structure and evolve the data model on PostgreSQL and BigQuery.

• Implement and improve CI/CD pipelines with GitHub Actions, Docker, Kubernetes.

• Industrialize infrastructure and environments following IaC, observability and performance best practices.

• Set up and maintain monitoring & alerting with Datadog, Sentry (dashboards, intelligent alerting).

Tech Stack

• Languages / Backend: Python (FastAPI, Django, Flask)

• Databases: PostgreSQL, BigQuery

• Cloud: GCP (Compute, Pub/Sub, Cloud Run, …)

• Observability: Datadog, Sentry

• CI/CD & Ops: GitHub Actions, Docker, Kubernetes

Profile

• 7+ years of experience in backend Python on complex web architectures.

• Strong experience with microservices and high-traffic / scale-up environments.

• Solid knowledge of scalability, performance tuning, monitoring & observability.

• Strong understanding of CI/CD and cloud environments (ideally GCP).

• Product-oriented mindset, able to balance robust architecture and business impact.

• Excellent communication skills and fluent English, comfortable in distributed teams.