Senior Java Engineer (Spring Boot)

TL;DR

Senior Java Engineer (Spring Boot): lead the test-driven migration of a legacy Java EE application to a modern Spring Boot architecture, including transformation from MySQL to MongoDB with an accent on analyzing existing components, designing clean services, and data model transformation. Focus on writing unit/integration tests prior to implementation, executing incremental migration with parallel validation, and ensuring performance parity with the legacy application.

Location: PL-Remote (Poland)

Company

Custom product engineering company supporting multinational organizations and scaling startups, with a global team of over 4,000 professionals and delivery centers in Wrocław and Gdańsk, Poland.

What you will do

• Analyze existing Java EE components and document business logic
• Design clean, testable Spring Boot services and data access interfaces
• Plan and execute MySQL to MongoDB data model transformation
• Write unit/integration tests prior to implementation
• Execute incremental migration with parallel validation
• Ensure performance parity with legacy application

Requirements

• Poland-based remote work
• Java/Spring Boot: strong experience building enterprise applications, REST APIs, and data access layers with Spring Data
• Jakarta EE/Java EE: ability to analyze and deconstruct legacy components (EJBs, JPA, CDI)
• MySQL: deep understanding of relational data models and query optimization
• MongoDB: experience with NoSQL patterns, document modeling, and Spring Data
• TDD/Unit Testing: proven track record with JUnit, Mockito, Testcontainers

Nice to have

• Python for scripting, automation, and migration tooling
• LLM/AI tools for code analysis, conversion, and documentation
• Kafka for event-driven architectures
• Docker/Kubernetes for containerized deployments

Culture & Benefits

• Strong community with top professionals in a friendly, open-door environment
• Growth focus on large-scale projects with global impact
• Tailored learning: internal events, Udemy, language courses, company-paid certifications
• Endless opportunities via internal mobility and diverse domains
• Flexibility with full remote working possibilities
• Company-paid medical insurance, mental health support, financial & legal consultations