Principal Java Engineer (Individual Contributor) 6-Month Contract | Outside IR35 | Paddington (3 days/week)

We are partnering with a leading UK retail organisation on a significant payments and platform transformation. We seek a Principal Java Engineer to join as a hands‑on individual contributor, playing a pivotal role within a dynamic engineering team.

This technically demanding position centres on designing, building, and scaling high-volume, mission‑critical payment systems. You will remain deeply involved in coding while influencing design and technical direction.

The Role

As a Principal Java Engineer, you will design and develop scalable backend services that facilitate secure payment transactions at scale. The environment is modern, cloud‑native, and prioritises event‑driven architecture and high performance.

Key Responsibilities

• Design and develop backend services using Java (Spring Boot or Micronaut)
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