Backend Java Developer - Freelance

We are looking for a Senior Backend Java Developer to join the transformation of a strategic digital product enabling connectivity with external sales channels such as marketplaces, social commerce and quick-commerce platforms. The role focuses on contributing to a major architecture rebuild in Java Spring Boot, within a cloud-native environment, with strong scalability, reliability, and real-time stock/price synchronization challenges.

The consultant will join a London-based feature team, with an expected presence of 3 days per week onsite. Fluent English is mandatory; French would be a plus. Target start date is June. Local compliance constraints, including UK market regulations and IR35, must also be taken into account.

Key responsibilities

• Play a leading role in the architectural rebuild of an existing product into a modern Java Spring Boot stack.

• Design and optimize technical connectors for external sales channels including marketplaces, social commerce and quick-commerce platforms.

• Rebuild and stabilize catalog publication flows, including category mapping, product variant synchronization and asynchronous marketplace APIs.

• Contribute to the migration of complex business rules related to pricing, stock filtering and fulfillment decisions.

• Ensure highly reliable real-time synchronization of stock and pricing data.