Senior Full Stack Developer Java React

We're looking for a skilled and proactive Senior Full Stack Developer with strong expertise in Java and React to join our engineering team. In this role, you'll take part in designing and building scalable web applications end to end - from robust backend services to modern, responsive frontends. Responsibilities: Provide technical expertise and guidance to the engineering team, including conducting code reviews, and fostering a culture of excellence in software development practices Write high-quality, maintainable code for critical components, features, or modules of the software application, while also contributing to the overall codebase and enforcing coding standards and best practices Analyze and solve complex technical problems, including performance bottlenecks, scalability challenges, and system failures, through systematic debugging, root cause analysis, and collaboration with cross-functional teams Refactoring and improving existing codebase to enhance maintainability, extensibility, and readability, while also identifying and addressing technical debt and legacy code issues Create and maintain technical documentation, including design documents, architecture diagrams, and best practices guides, to facilitate knowledge sharing, onboarding, and collaboration within the team Ensure the overall quality and reliability of software products through rigorous testing practices, including unit tests, integration tests, and end-to-end tests, as well as promoting a culture of testing and quality assurance within the team Min requirements: 2–3 days per week from the Warsaw office Strong knowledge and hands-on experience in backend development with Java & Spring Boot Deep understanding of RESTful web services and microservices architecture Expertise in API development (designing interactions between platform components) Ability to develop frontend applications using JavaScript, HTML, CSS, React Experience in user interface (UI) design Proficiency in writing maintainable code following TDD/BDD paradigms Solid grasp of Clean Code principles : SOLID, KISS, DRY, Clean Architecture Strong experience with containerization & orchestration (Docker, Kubernetes) Hands-on experience with application development lifecycle and CI/CD pipelines Practical knowledge of authentication and authorization methods Practical experience with secure connectivity (mTLS, Message Level Encryption, etc.) Would be a plus: Kotlin experience or willingness to learn Knowledge of encryption/decryption methods and tools , including HSMs (Hardware Security Modules) Broader experience with enterprise-level security integrations We offer: Opportunity to work on bleeding-edge projects Work with a highly motivated and dedicated team Competitive salary Flexible schedule Benefits package - medical insurance, sports Corporate social events Professional development opportunities Well-equipped office About us: Grid Dynamics (NASDAQ: GDYN) is a leading provider of technology consulting, platform and product engineering, AI, and advanced analytics services. Fusing technical vision with business acumen, we solve the most pressing technical challenges and enable positive business outcomes for enterprise companies undergoing business transformation. A key differentiator for Grid Dynamics is our 8 years of experience and leadership in enterprise AI , supported by profound expertise and ongoing investment in data , analytics , cloud & DevOps , application modernization and customer experience . Founded in 2006, Grid Dynamics is headquartered in Silicon Valley with offices across the Americas, Europe, and India.