Principal Java Engineer - Retail

Mindera; Greater London; On-site; GBP 70,000 - 90,000; Full time

Job summary

Mindera is seeking a Principal Java Engineer to join their team in Greater London. This six-month contract outside IR35 requires strong experience in Java 17+, as well as leadership in technical challenges and solutions.

Your role will include crafting secure, high-volume payment services, mentoring engineers, and ensuring best practices in software development. If you have a solid understanding of payment systems and cloud infrastructure, we want you!

Qualifications

• Proven experience as a Principal Java Engineer in backend environments.
• Strong experience in Java 17+, with a willingness to learn Kotlin.
• Hands-on knowledge of Kafka and Microservices required.

Responsibilities

• Lead technical deep dives and propose solutions.
• Write high-quality Java code for robust services.
• Mentor junior engineers and drive technical excellence.

Skills

Java 17+

Spring Boot

Microservices

Kafka

Agile/Scrum

Cloud infrastructure (Azure)

Regulatory standards (PCI DSS, SCA, PSD2)

Strong communication skills

Tools

Kubernetes

Terraform

GitHub Actions

OpenTelemetry

Dynatrace

Job description

Requirements

• Proven experience as a Principal Java Engineer in backend-heavy environments in teams having multiple levels of engineering
,
• Strong experience in Java 17+, ideally with experience in using Spring Boot or Micronaut. Kotlin experience is a bonus. If the applicant does not have experience they must show willingness to learn Kotlin
,
• Hands-on knowledge of Kafka, event-driven architecture, enterprise integration patterns and Microservices
,
• Solid understanding of payment systems and PSP integrations, including fraud, tokenisation, and settlement flows
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• Experience with cloud infrastructure (Azure preferred), CI/CD, and Kubernetes
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• Working knowledge of regulatory and compliance standards (PCI DSS, SCA, PSD2)
,
• Strong communication skills and the ability to explain complex technical concepts to a range of audiences
,
• Experience working in Agile/Scrum teams with a DevOps culture and test-driven mindset

What the job involves

• At Mindera, we craft software with people we love. We’re looking for a Principal Java Engineer with strong Retail experience who can join our crew!
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• This is a six month contract that sits outside IR35
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• Lead technical deep dives and knowledge sharing in the teams, anticipating challenges and proposing solutions
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• Start influencing product and business decisions
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• Write high-quality Java code using frameworks such as Spring Boot or Micronaut
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• Build robust services that support secure, high-volume payment transactions
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• Develop integrations with acquiring banks, payment gateways, and fraud detection tools
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• Build and support cloud-native systems on the cloud (preferably Azure) using Terraform and Kubernetes
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• Manage CI/CD pipelines using GitHub Actions and ensure smooth delivery to production
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• Own monitoring, alerting, and observability, using tools like OpenTelemetry and Dynatrace
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• Champion secure coding practices and data protection across services
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• Work closely with product owners, engineering leads, and other stakeholders to shape technical solutions
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• Mentor and support more junior/mid/senior engineers, driving technical excellence across the board
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• Help establish and promote best practices around code review, testing, delivery, and operational support
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• Continuously improve platform reliability, performance, and cost-efficiency
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• Stay up-to-date with technology trends and proactively identify innovation opportunities