Principal Java Engineer – Retail (6‑month contract)

About the role

Mindera is seeking a Principal Java Engineer with deep retail payment experience to join a leading UK retailer’s team. This is a six‑month contract role based in Paddington, requiring three days a week on‑site.

Key responsibilities

• Lead technical deep‑dives, share knowledge and anticipate challenges.
• Influence product and business decisions while delivering high‑quality Java code.
• Build robust, secure services for high‑volume payment transactions using Spring Boot or Micronaut.
• Develop integrations with acquiring banks, payment gateways and fraud detection tools.
• Design and maintain cloud‑native systems on Azure using Terraform and Kubernetes.
• Manage CI/CD pipelines with GitHub Actions and ensure reliable production releases.
• Own monitoring, alerting and observability using OpenTelemetry and Dynatrace.
• Champion secure coding practices and compliance with PCI DSS, SCA and PSD2.
• Mentor junior and mid‑level engineers and promote best practices.
• Continuously improve platform reliability, performance and cost‑efficiency.

Required profile

• Proven experience as a Principal Java Engineer in backend‑heavy, multi‑level teams.
• Strong expertise in Java 17+ with Spring Boot or Micronaut; Kotlin a plus.
• Hands‑on knowledge of Kafka, event‑driven architecture and microservices.
• Solid understanding of payment systems, PSP integrations, fraud, tokenisation and settlement flows.
• Experience with Azure cloud, Terraform, Kubernetes and CI/CD pipelines.
• Familiarity with regulatory standards such as PCI DSS, SCA and PSD2.
• Excellent communication skills and ability to explain complex concepts.
• Agile/Scrum experience with a DevOps and test‑driven mindset.

Required skills

• Java 17+
• Spring Boot
• Micronaut
• Kotlin (optional)
• Kafka
• Event‑driven architecture
• Microservices
• Azure
• Terraform
• Kubernetes
• GitHub Actions
• OpenTelemetry
• Dynatrace
• PCI DSS
• SCA
• PSD2

What we offer

• Competitive daily rates.
• Six‑month contract outside IR35 with possible extension.
• Friendly, welcoming team environment.
• Opportunity to work with one of the UK’s leading retailers.