Principal Java Developer

RE Partners; Milton Keynes; Hybrid; GBP 90,000 - 130,000; Full time

Job summary

RE Partners is seeking a Principal Java Engineer to join our high-performing team in the UK. You will own the design and optimization of low-latency, high-throughput backend systems for payments, building secure RESTful APIs and scalable microservices.

In this hybrid role, you will deploy and monitor on OpenShift and AWS, integrate with MongoDB, and mentor peers while driving architectural decisions and observability enhancements across services.

Qualifications

• 10+ years in Java with focus on performance and memory optimization.
• Proficient in Mongo, Spring and microservice-based architecture.
• Proven experience with low-latency, high-throughput applications (sub-millisecond responses a plus).
• Hands-on with OpenShift and/or Kubernetes deployment.
• Strong AWS experience (ECS, EKS, Lambda, S3).
• Strong communication and bias toward action and opinionated design.

Responsibilities

• Design, develop, and optimize low-latency, high-throughput backend systems using Java.
• Build and maintain RESTful APIs and microservices powering secure payment workflows.
• Work with messaging standards and protocols used in financial transactions.
• Deploy, monitor, and scale applications in OpenShift and AWS.
• Integrate with MongoDB and other data stores for real-time data management.
• Collaborate with DevOps, Product, and QA to deliver production-grade solutions.
• Drive architectural changes and mentor peers.
• Drive performance tuning, fault tolerance, and observability improvements.

Skills

Java

Spring

Microservices

OpenShift

AWS

MongoDB

Low-latency

Tools

OpenShift

Kubernetes

MongoDB

AWS

REST APIs

Job description

We are seeking an experienced and opinionated Principal Java Engineer to join our high-performing engineering team, working on low latency, high-throughput systems in the payments processing domain. This hybrid role is based in the UK and offers the opportunity to build scalable, real-time services using modern technologies.If you’re passionate about performance, have strong Core Java and SpringBoot expertise, and thrive in a collaborative yet opinionated engineering culture, we want to hear from you

.Key Responsibilities

• :Design, develop, and optimize low-latency, high-throughput backend systems using Java
• .Build and maintain RESTful APIs and microservices that power secure payment workflows
• .Work with messaging standards and protocols commonly used in financial transactions
• .Deploy, monitor, and scale applications in Red Hat OpenShift and AWS cloud environments
• .Integrate with MongoDB and other NoSQL/SQL datastores for real-time data management
• .Collaborate with DevOps, Product, and QA teams to ensure production-grade solutions
• .Drive architectural changes, advocate for best practices, and provide mentorship to peers
• .Drive performance tuning, fault tolerance, and observability improvements across services

.
Required Skills & Experienc

• e:10+ years of experience in Java development with a focus on performance and memory optimizatio
• n.Proficient in Mongo, Spring and microservice-based architectur
• e.Proven experience with low-latency, high-throughput applications (sub-millisecond response times a plus
• ).Hands-on experience deploying applications on Red Hat OpenShift and/or Kubernete
• s.Strong cloud experience with AWS services such as ECS, EKS, Lambda, S3, et
• c.Strong communication skills and a bias toward action and opinionated design decision

s.
Nice to Ha

• ve:Familiarity with messaging systems (Kafka, RabbitMQ, et
• c.)Prior experience in Payments Processing, financial services, or banking syste
• ms.Exposure to container security and performance tuning on OpenShi
• ft.Knowledge of payment gateways, ISO 20022, or SWIFT forma
• ent:Hybrid work model in London,
• UK.Collaborative, fast-paced, and engineering-driven cult
• ure.Emphasis on engineering autonomy, architectural decision-making, and clean

bonus
Equal Opportunity Empl

ier: We are an equal opportunity employer and welcome applications from all qualified individuals regardless of race, color, religion, gender, sexual orientation, gender identity or expression, national origin, age, disability, or veteran status.