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For Companies At a Glance
- Tasks: Build high-performance, event-driven systems for real-time payments.
- Company: Leading payments consultancy with a focus on innovation.
- Benefits: Competitive salary, annual bonus, and hybrid working options.
- Why this job: Make a global impact by powering instant transactions for major banks.
- Qualifications: Strong Java experience and knowledge of asynchronous programming.
- Other info: Join a dynamic team with a product-led, engineering-first culture.
The predicted salary is between 80000 - 120000 £ per year.
London – Hybrid (1 day per week onsite)
Are you a senior, hands-on Engineer who thrives in event-driven, asynchronous environments? Do you enjoy building low-latency, high-throughput distributed systems where correctness, resilience, and performance really matter?
This is an opportunity to work at the core of real-time payments infrastructure, helping to power instant transactions for some of the world’s largest banks. We’re hiring on behalf of a leading payments consultancy delivering mission-critical, event-driven platforms that integrate deeply with bank infrastructure to enable secure, real-time payments at global scale.
What You’ll Be Doing
- You’ll play a senior individual-contributor role within a high-performing engineering team, building asynchronous, message-driven systems designed for scale, resilience, and near-zero downtime.
- Design and implement high-throughput, low-latency systems processing millions of real-time payment events.
- Build event-driven architectures using modern Java and reactive frameworks.
- Work extensively with non-blocking I/O, asynchronous flows, back-pressure, and concurrency.
- Contribute to system and API design, focusing on scalability, fault tolerance, and observability.
- Collaborate closely with architects, engineers, and client teams across Europe.
- Operate in Agile environments (Scrum / Kanban) with a strong engineering culture.
Tech Stack (current & evolving):
- Java 17+, Spring WebFlux, Akka, Kafka, reactive streams, distributed messaging, cloud-native tooling.
What You Bring
- We’re looking for engineers who enjoy thinking in events, streams, and asynchronous workflows, and who take pride in building systems that perform under pressure.
- Strong hands-on experience with Java 11+ (ideally Java 17) in production environments.
- Deep understanding of asynchronous and reactive programming models.
- Proven experience with event-driven architectures and real-time messaging (Kafka, JMS, Akka, etc.).
- Solid grasp of distributed systems concepts: concurrency, idempotency, fault tolerance, and resilience.
- Experience building and testing production-grade systems using TDD/BDD and CI/CD pipelines.
- Comfortable working on complex, long-lived systems where performance and reliability are critical.
Bonus (not essential):
- Experience in banking, payments, or financial systems, or if you’ve built real-time platforms at scale.
What’s In It for You
- £100,000 – £115,000 base salary (DOE).
- 20% annual bonus.
- Work on event-driven, real-time systems with global impact.
- Hybrid working – 1 day a week onsite (more if you prefer).
- Exposure to major international banks and payment networks.
- A product-led, engineering-first environment where technical decisions matter.
Senior Java Engineer - Reactive (Spring WebFlux) in London employer: Fynity
Contact Detail:
Fynity Recruiting Team
StudySmarter Expert Advice 🤫
We think this is how you could land Senior Java Engineer - Reactive (Spring WebFlux) in London
✨Tip Number 1
Network like a pro! Reach out to your connections in the industry, especially those who work with event-driven systems or in payments. A friendly chat can lead to insider info about job openings that aren't even advertised yet.
✨Tip Number 2
Show off your skills! If you’ve built any projects using Java 17+, Spring WebFlux, or reactive frameworks, make sure to showcase them. A personal portfolio or GitHub repo can really set you apart from the crowd.
✨Tip Number 3
Prepare for technical interviews by brushing up on your knowledge of asynchronous programming and distributed systems. Practice coding challenges that focus on low-latency and high-throughput scenarios to impress your interviewers.
✨Tip Number 4
Don’t forget to apply through our website! It’s the best way to ensure your application gets seen by the right people. Plus, we love seeing candidates who are proactive about their job search!
We think you need these skills to ace Senior Java Engineer - Reactive (Spring WebFlux) in London
Some tips for your application 🫡
Tailor Your CV: Make sure your CV highlights your experience with Java, Spring WebFlux, and event-driven architectures. We want to see how your skills align with the role, so don’t be shy about showcasing relevant projects!
Craft a Compelling Cover Letter: Your cover letter is your chance to shine! Share your passion for building low-latency systems and your experience in asynchronous environments. Let us know why you’re excited about this opportunity at StudySmarter.
Showcase Your Problem-Solving Skills: In your application, give examples of how you've tackled challenges in previous roles, especially around performance and reliability. We love engineers who can think on their feet and come up with innovative solutions!
Apply Through Our Website: We encourage you to apply directly through our website. It’s the best way for us to receive your application and ensures you don’t miss out on any important updates from our team!
How to prepare for a job interview at Fynity
✨Know Your Tech Stack Inside Out
Make sure you’re well-versed in Java 17+, Spring WebFlux, and the other technologies mentioned in the job description. Brush up on your knowledge of asynchronous programming and event-driven architectures, as these will likely be key discussion points during your interview.
✨Showcase Your Problem-Solving Skills
Prepare to discuss specific challenges you've faced in building low-latency, high-throughput systems. Be ready to explain how you approached these problems, the solutions you implemented, and the outcomes. This will demonstrate your hands-on experience and ability to thrive under pressure.
✨Familiarise Yourself with Agile Methodologies
Since the role operates in Agile environments, it’s crucial to understand Scrum and Kanban principles. Be prepared to talk about your experience working in Agile teams and how you’ve contributed to a strong engineering culture in previous roles.
✨Ask Insightful Questions
Interviews are a two-way street! Prepare thoughtful questions about the company’s approach to real-time payments, their engineering practices, and how they handle scalability and resilience. This shows your genuine interest in the role and helps you assess if it’s the right fit for you.
