Senior Java Engineer — Low-Latency Payments & Cloud Microservices

RE Partners Consulting; Warszawa; On-site; PLN 240,000 - 360,000; Full time

Job summary

RE Partners Consulting is seeking a Senior Java Engineer in Warszawa to design and optimize low-latency, high-throughput backend systems in the payments domain. You will develop RESTful microservices, integrate with MongoDB, and deploy on OpenShift and AWS, while mentoring peers and driving architectural improvements.

The role requires 10+ years in Java, strong Spring/MongoDB experience, and a track record of performance-focused delivery in a collaborative, engineering-driven culture.

Qualifications

• 10+ years of Java development with a focus on performance and memory optimization.
• Proficient in MongoDB, Spring and microservice-based architecture.
• Proven experience with low-latency, high-throughput applications (sub-millisecond response times a plus).
• Hands-on experience deploying applications on OpenShift and/or Kubernetes.
• Strong cloud experience with AWS services such as ECS, EKS, Lambda, S3, etc.
• Strong communication skills and a bias toward action and opinionated design decisions.

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.

Skills

Java

Performance optimization

Low-latency design

Mentorship

Tools

Spring Boot

MongoDB

OpenShift

Kubernetes

AWS

REST APIs

Microservices

Job description

RE Partners Consulting is seeking a Senior Java Engineer in Warszawa to design and optimize low-latency, high-throughput backend systems in the payments domain. You will develop RESTful microservices, integrate with MongoDB, and deploy on OpenShift and AWS, while mentoring peers and driving architectural improvements.

The role requires 10+ years in Java, strong Spring/MongoDB experience, and a track record of performance-focused delivery in a collaborative, engineering-driven culture.