Senior Java Developer

Quick Facts

• Role: Senior Java Developer (backend)
• Stack: Java 21, Spring Boot 3.4, Spring Data JPA/Hibernate, PostgreSQL (Liquibase), REST/SOAP
• Work model: Warsaw/Wola + remote
• Engagement: Long-term B2B
• Rate: 170 PLN net/hour
• Start: asap

Description

Design, develop, and maintain the backend of enterprise applications using Java 21 and the Spring ecosystem. Create and integrate REST and SOAP APIs, work with relational databases using Liquibase-based migrations, and support production systems through monitoring, debugging, and performance/code-quality improvements. Maintain technical and architectural documentation (Enterprise Architect) and help shape system architecture with security and scalability in mind.

Responsibilities

• Develop and maintain backend components using Java 21 and Spring (Spring Boot 3.4, JPA/Hibernate)
• Build and integrate REST and SOAP APIs
• Work with PostgreSQL/Oracle databases and manage schema changes (Liquibase)
• Monitor systems, analyze risks, and plan development/migrations
• Collaborate with and coordinate other development teams; provide technical support to other groups
• Test, debug, and deploy new features with performance and code-quality optimization
• Prepare technical and architectural documentation in Enterprise Architect
• Define system architecture requirements (business, technical, security, scalability) and coding/deployment standards

Requirements

• Minimum 3 years of commercial Java development (preferred: Java 21)
• Strong Java/JVM knowledge: object-oriented & functional programming, multithreading, memory management, JVM mechanisms
• Practical experience building and maintaining enterprise backend applications
• Experience on high-availability and/or highly integrated systems
• Hands-on delivery of changes across business logic, integrations, databases, and tests
• Ability to diagnose production and maintenance issues and analyze logs
• Strong Spring Boot (preferred 3.4), Spring Framework, Spring Data JPA, JPA/Hibernate
• Ability to design REST controllers, application/business logic, data repositories, and integration adapters
• Practical relational DB experience: PostgreSQL and Oracle
• Strong SQL, data modeling, and query optimization
• Experience with DB schema migration tools, especially Liquibase
• Experience designing and implementing integrations: REST API, SOAP/Web Services, JSON, XML, OpenAPI, WSDL/XSD
• Knowledge of Git and Maven or Gradle; unit testing with JUnit and Mockito (or equivalents)
• Ability to create unit and integration tests
• Practical log/bug diagnosis and application performance optimization
• Practical knowledge of JIRA and Confluence
• Ability to prepare and update technical documentation
• Experience using AI tools that support software development (code generation, tests, refactoring, code review support, log/error analysis, documentation)
• Know and follow information security rules when using AI tools
• Independence, responsibility, analytical problem-solving, and code-review collaboration
• Ability to estimate tasks, flag technical risks, and align with analysts, testers, architects, and maintenance teams
• Commitment to code quality, security, and maintainability

Benefits

• Long-term cooperation
• Remote work allowed (Warsaw/Wola)
• B2B employment model
• 170 PLN net/hour rate
• Start: asap