Senior Java Developer

Billennium; Warszawa; Hybrid; PLN 200,000 - 320,000; Full time

Benefits offered by this job

Udemy for Business

Worksmile platform

Remote/hybrid options

International collaboration

Job summary

Billennium is seeking a Senior Java Developer to support the development and optimization of Camunda BPMN-based business processes within the Digital Product Center. You will work on end-to-end banking solutions, building scalable microservices and secure REST integrations with internal and external systems.

Join a dynamic, agile team focusing on cloud-native platforms with Docker, Kubernetes, and Spring Cloud, while collaborating with product owners, analysts and DevOps engineers across

Qualifications

• 5 years of hands-on experience developing Spring Boot applications.
• Proficiency in Java 11 and Spring Boot.
• Familiarity with Maven and HTTP protocol.
• Solid understanding of PKI, TLS, and JWT-based auth.
• Experience with relational databases (PostgreSQL, MySQL).
• Experience with GitLab, Docker, Jenkins, or CI/CD toolchains.

Responsibilities

• Design and implement Camunda BPMN business workflows.
• Develop and maintain Spring Boot microservices.
• Build scalable REST APIs and integrations.
• Model data using PostgreSQL/MySQL and NoSQL (MongoDB/Redis).
• Implement security using OAuth2, JWT, and best practices.
• Develop event-driven integrations with Kafka and RabbitMQ.
• Write unit and integration tests with JUnit 5, Mockito, AssertJ.
• Contribute to code reviews, static analysis, and development standards.
• Support CI/CD and deployment automation with Jenkins, GitHub Actions, or GitLab CI.
• Collaborate with Product Owners, Analysts, Architects, and DevOps in an Agile environment.
• Contribute to cloud-native platform using Docker, Kubernetes, and Spring Cloud.

Skills

Java 11

Spring Boot

REST APIs

Maven

PostgreSQL

MySQL

NoSQL

OAuth2

JWT

Apache Kafka

RabbitMQ

JUnit 5

Mockito

CI/CD

Jenkins

GitHub Actions

GitLab CI

Docker

Kubernetes

Spring Cloud

Security

CI/CD tooling

Tools

Docker

Kubernetes

IntelliJ IDEA

Jenkins

Job description

Our client is a leading international banking institution undergoing a major digital transformation. The organization develops modern digital platforms and banking solutions that support millions of customers across retail and corporate banking channels. The role offers an opportunity to work on large-scale, business-critical systems in a dynamic and technology-driven environment.

We are looking for a professional to support the development and optimization of business processes based on the Camunda BPMN workflow engine within the Digital Product Center. The platform is responsible for the end-to-end processing of banking products across digital channels, enabling automation, orchestration, and monitoring of business workflows.

What You Will Do

• Designing and implementing business workflows using Camunda BPMN.
• Developing and maintaining Spring Boot-based microservices supporting banking products and digital channels.
• Building scalable and secure REST APIs and integrations with internal and external systems.
• Designing and optimizing data models using both relational databases (PostgreSQL, MySQL) and NoSQL technologies (MongoDB, Redis).
• Implementing security mechanisms based on OAuth2, JWT, and industry best practices.
• Developing event-driven integrations using Apache Kafka and RabbitMQ.
• Creating automated unit and integration tests using JUnit 5, Mockito, AssertJ, and Test containers.
• Participating in software quality initiatives, including code reviews, static code analysis, and continuous improvement of development standards.
• Supporting CI/CD processes and deployment automation using tools such as Jenkins, GitHub Actions, or GitLab CI.
• Working closely with Product Owners, Analysts, Architects, and DevOps Engineers in an Agile (Scrum/Kanban) environment.
• Contributing to the evolution of a modern cloud-native platform leveraging Docker, Kubernetes, and Spring Cloud technologies.

Requirements

• 5 years of hands-on experience developing and maintaining commercial, production-grade applications based on the Spring Boot framework.
• Proficiency in Java 11, Spring Boot, and the HTTP protocol.
• Experience with software build automation and dependency management tools, particularly Maven.
• Solid understanding of core security concepts and technologies, including Public Key Infrastructure (PKI), symmetric and asymmetric encryption, TLS, and JWT-based authentication and authorization.
• Experience working with transactional relational databases from an application development perspective.
• Hands-on experience with GitLab, Docker, IntelliJ IDEA, Jenkins, or equivalent development and CI/CD toolchains.

Professional development – continuous learning opportunities and internal mobility. Comprehensive benefits – enjoy Udemy for Business and Worksmile platform. Flexibility – adaptable working hours and remote/hybrid work options. Global collaboration – work with diverse international teams across continents. Innovative environment – be part of a forward-thinking, growth-oriented workplace. Team-building traditions – including our annual company event.