Principal Java Software Engineer

Overview

This range is provided by Fynity. Your actual pay will be based on your skills and experience — talk with your recruiter to learn more.

Principal Software Engineer (Java)

London – 1 day a week onsite

Join a FinTech Powering the Future of Payments

Are you a seasoned individual contributor looking for a step up into a senior position within a high-performing team within the world of Banking/Payments? Are you passionate about high-throughput, real-time systems? This is your opportunity to help shape the core technology that powers instant payments for some of the world’s largest Banks.

We’re hiring on behalf of a leading payments consultancy, delivering cutting-edge solutions that integrate seamlessly with bank infrastructure to enable real-time, secure transactions across the globe.

What You’ll Be Doing

You’ll be the focal point of a high-performing engineering team building asynchronous, event-driven systems using modern Java technologies.

• Design and build scalable, high-availability systems processing millions of real-time transactions
• Work with Java 17+, Spring WebFlux, AKKA, Kafka, and more
• Write clean, testable code using TDD and BDD
• Contribute to architectural decisions in a fast-evolving codebase
• Collaborate within Agile teams (Kanban/Scrum)

What You Bring

We’re looking for engineers who are pragmatic, performance-focused, and thrive on solving complex distributed systems problems.

• Strong hands-on experience with Java 11+ (ideally Java 17)
• Solid knowledge of Reactive Programming (e.g., Spring WebFlux, AKKA)
• Experience with event-driven architecture, real-time messaging systems (Kafka, JMS)
• Familiarity with asynchronous request handling, scalability, and system resilience
• Agile mindset, with TDD/BDD and CI/CD experience

Bonus: Background in Banking/Payments is helpful but not required – if you’ve built high-performance, real-time systems, we want to talk to you.

What’s In It for You

• Work with cutting-edge tech on globally impactful systems
• Hybrid working – 1 day a week (or more if you’d like!)
• Opportunity to collaborate with major global banks
• Fast-paced, product-led environment where your voice matters

If you\'re a motivated Senior/Principal/Staff Java Software Engineer ready to tackle complex challenges and deliver meaningful change, hit apply – and shape the future of payments with us.

Employment and Seniority

• Seniority level: Mid-Senior level
• Employment type: Full-time
• Job function: Engineering, Information Technology, and Other
• Industries: Banking, Financial Services, and Software Development