Java Software Engineer

Senior Java DeveloperContract: 6 months

Location: Remote (must be based in Poland)

Start date: ASAP

Overview

We are looking for a Senior Backend Java Developer to join a high‑impact engineering team working on a sophisticated Data Fabric platform. The platform is responsible for managing user access, enforcing complex entitlement and policy rules, and manipulating SQL queries in a deterministic and extensible way.

You’ll be building and evolving core backend Java services, working closely with technologies such as Apache Calcite, Spring, and Starburst integrations, and contributing to robust, highly testable pipelines used in a data‑intensive environment.

This is a hands‑on role for someone who enjoys deep technical problem‑solving, clean architecture, and working close to complex data and query engines.

Responsibilities

• Design and implement core backend logic for Data Fabric services
• Build and extend rule definitions for access control and policy enforcement
• Work with SQL parsing, validation, and query transformation pipelines
• Integrate with other backend services and maintain well‑documented APIs
• Own and contribute to API specifications with continuous documentation practices
• Maintain high test coverage using JUnit 5, Mockito, and BDD (Cucumber)
• Take ownership of CI/CD pipelines, code quality, and observability
• Collaborate with engineers to ensure performance, correctness, and scalability

Required Skills & Experience

• Strong experience building backend services using Java (17 or 21)
• Solid experience with Spring / Spring Core
• Deep knowledge of JDBC, SQL parsing and validation
• Good experience with SQL planning and query optimisation
• Strong understanding of data structures and algorithms
• Proven testing mindset with JUnit 5, Mockito, and Cucumber
• Experience designing deterministic and reliable test suites
• Clean architecture mindset: dependency injection, modular design
• Familiarity with modern development tooling:
• Docker, Jenkins, Maven
• Code quality and coverage tools such as Checkstyle and JaCoCoNice to Have

• Experience working with Apache Calcite
• Experience with Starburst or other data virtualisation technologies
• JVM performance tuning and optimisation experience
• Experience with application networking interfaces:
• HTTP / REST
• gRPC / RPC
• Raw sockets