Principal Java Engineer

RE Partners; Warszawa; Hybrid; PLN 454,000 - 655,000; Full time

Benefits offered by this job

Hybrid work model in Warsaw, Poland

Job summary

RE Partners is seeking an experienced Principal Java Engineer to join our high-performing engineering team. You will work on low-latency, high-throughput backend systems in the payments processing domain, with hybrid work based in the UK.

You will design and optimize services, build secure payment workflows, and scale infrastructure across OpenShift, AWS, and diverse data stores while mentoring peers in an opinionated engineering culture.

Qualifications

• 10+ years of Java development experience focusing on performance and memory optimization.
• Proficient in Mongo, Spring and microservice-based architecture.
• 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 (ECS, EKS, Lambda, S3, etc.).
• Excellent communication with 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 used in financial transactions.
• Deploy, monitor, and scale applications in OpenShift and AWS cloud environments.
• Integrate with MongoDB and other datastores for real-time data management.
• Collaborate with DevOps, Product, and QA to ensure production-grade solutions.
• Drive architectural changes, advocate best practices, and mentor peers.
• Drive performance tuning, fault tolerance, and observability improvements across services.

Skills

Java performance

Low-latency design

Microservices

REST APIs

Cloud computing

Tools

MongoDB

SpringBoot

OpenShift

Kubernetes

AWS

Job description

Who We Are:

We are a fast growing business and technology consultant company co-founded in 2019. We offer a custom-tailored, white-glove engineering service fit for our clients, because a digital transformation is more than just technology. With a successful track record of being a preferred vendor for Fortune 500 companies and as a trusted partner for some of the industry’s leading companies, our global talent has helped many clients achieve their goals.

The 3 G’s of RE:

“Get Shit Done.”

“Get Over Shit.”

“Give a Shit.”

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 & Experience:

• 10+ years of experience in Java development with a focus on performance and memory optimization.
• Proficient in Mongo, 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 Red Hat 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.

Nice to Have:

• Familiarity with messaging systems (Kafka, RabbitMQ, etc.)
• Prior experience in Payments Processing, financial services, or banking systems.
• Exposure to container security and performance tuning on OpenShift.
• Knowledge of payment gateways, ISO 20022, or SWIFT formats.
• Hybrid work model in Warsaw, Poland.
• Collaborative, fast-paced, and engineering-driven culture.
• Emphasis on engineering autonomy, architectural decision-making, and clean code

Equal Opportunity Employer:

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.