Senior Backend Python Engineer - Freelance

Job description

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

The role is embedded within payment-related teams, working on business-critical systems that power payment flows, transaction processing, financial data reliability, and integrations with the broader platform ecosystem.

Mission – Key Responsibilities (Tech-focused)

Design, develop, and optimize backend services in Python (FastAPI, Django, or Flask) for payment and transaction-related systems.

Contribute to the evolution of a resilient microservices architecture supporting payment workflows, transaction orchestration, and financial operations.

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