Senior Java Developer Build Java 21 applications powering taxation, savings and investment products in an international finance team. Hybrid Warsaw, Gdańsk or Gdynia role, up to 150 PLN/h net + VAT. Senior Java Developer Rate: Up to 150 PLN/h net + VAT (B2B) Location: Warsaw, Gdańsk, or Gdynia Work Model: Hybrid (3 days a week from the office / 50% remote) We are Optiveum , a specialized recruitment and contracting company. We are currently looking for a Senior Java Developer to join the team of our client, a prominent international company operating in the financial and investment sector. In this model, you will sign a B2B cooperation agreement directly with Optiveum. As a Senior Java Developer, you will be responsible for developing and enhancing our client's Java-based applications that handle taxation, account management, and investment processing for pension and savings products. Key Responsibilities Designing, developing, and maintaining Java applications supporting savings and investment products. Building robust calculation engines that ensure compliance with current tax regulations across multiple countries. Developing support for complex business processes, integrating with tax authorities, and generating customer-facing reports. Participating in the full software development lifecycle, including requirements analysis, design, coding, testing, and deployment. Collaborating with financial analysts to translate business requirements into technical solutions. Mentoring other developers, acting as a code reviewer or design sparring partner, and spreading practical engineering practices across the team. Responsibly utilizing AI-assisted development and automation tools to improve productivity, quality, and continuous learning. Must-Have Requirements Strong proficiency in Java (especially Java 21 ) and related frameworks ( Spring, Spring Boot, Hibernate ). Experience with relational databases and SQL (e.g., PostgreSQL ). Knowledge of messaging protocols such as JMS, MQ , etc. Knowledge of OpenAPI and AsyncAPI for producing and consuming data. Familiarity with version control systems ( Git ) and CI/CD pipelines. Solid understanding of software design patterns and Object-Oriented Programming (OOP) principles. Advanced English proficiency, allowing for smooth communication in an international environment. What Optiveum Offers A transparent B2B contract signed directly with Optiveum as your contracting party. Attractive hourly rate up to 150 PLN/h net + VAT . Ongoing operational support from Optiveum throughout the entire duration of our cooperation. The opportunity to work in a collaborative, international environment strongly influenced by a supportive Swedish organizational culture. A flexible hybrid working model. Specjalizacja / specialism IT Role BackEnd Developer Locations Warsaw , Gdańsk , Gdynia Remote status Hybrid About OPTIVEUM sp. z o.o. Optiveum is a recruitment and consulting company created based on our 20-plus years of experience in HR & IT services. We work for Clients located in Poland and abroad providing our local and international Candidates with Project-based or Permanent job opportunities in a remote or office-based model. COMPANY DATA Optiveum Sp. z o.o. ul. Tomasza Zana 43 lok. 2.1 20-601 Lublin, Poland nr KRS: 0000834436, NIP 7010975729 Contact us at: info (at) optiveum.com