Senior Java Developer

Join the engineering team to spearhead a critical backend migration from Node.js (Nest.js) to Java/Spring Boot for a specialized Self-Compliance platform. The platform enables enterprise companies to navigate, manage, and enforce labor laws alongside strict regulatory compliance frameworks. In this role, you will work closely with a TechLead and an internal team holding full domain knowledge, transitioning legacy services into a highly scalable, reactive microservices architecture while laying the foundation for long-term product maintenance and feature development.
Details

Start Date: ASAP / Strict July 2026 Start (Only currently available candidates can be considered).Duration: 6 months or longer.
Max Rate: 140 PLN/h.
Work Allocation: Full-time.
Security & Compliance Constraint: Strictly NO AI tools allowed (Tools like GitHub Copilot, ChatGPT, or similar automated code assistants are completely banned on this project).
Responsibilities
• System Migration: Re-architect and migrate the existing backend infrastructure from Nest.js (Node.js) over to Java and Spring Boot.
• Microservices & Reactive Design: Implement distributed, fault-tolerant microservices utilizing Netflix OSS and asynchronous, non-blocking reactive programming patterns.
• Database & Messaging Integration: Manage data persistence, caching mechanisms, and asynchronous message brokers to maintain high throughput and low-latency system data flow.
• Schema Evolution: Write and execute robust database migration scripts to smoothly transition underlying data structures without downtime.
• Quality Assurance: Guarantee code stability through thorough unit and integration testing.
• Cross-Functional Communication: Collaborate actively in regular project syncs with internal team members, the client, and the TechLead to refine system requirements.
Requirements
• Core Backend Stack: Expert commercial knowledge of Java and the Spring Boot ecosystem.
• Microservices Architecture: Deep familiarity with Netflix OSS for service discovery, routing, and resilience patterns.
• Reactive Programming: Practical experience using Spring Reactor to handle asynchronous data streams.
• Data & Cache Layer: Strong hands-on experience with PostgreSQL (relational) and Redis (caching/in-memory data structure store).
• Message Broker: Solid proficiency with RabbitMQ for event-driven message queuing.
• Database Versioning: Proven experience handling database changes via Liquibase.
• Testing Stack: Mastery of JUnit and Mockito for reliable test-driven or test-backed development.
Other Requirements
• Languages: Good English proficiency, allowing for smooth daily communication and clear understanding of complex business/legal requirements.
• Interpersonal Skills: Outstanding communication and teamwork capabilities for joint ownership of codebases.
• Legacy Ecosystem Context: Basic familiarity or comfort reading legacy system layouts spanning Nest.js, React.js, TypeScript, Docker, and Kubernetes is helpful to assist in extraction and migration mapping.