Senior Java Developer - Generative AI and Payments

Senior Java Developer – Gen AI & Payments Location: Krakow / Warsaw, Poland Experience: 8+ Years B2B Long term contract opportunity Job Summary We are looking for an experienced Senior Java Developer with 8+ years of software engineering experience, strong expertise in Java development, hands-on exposure to Generative AI technologies, and proven experience within the Payments / Financial Services domain. The successful candidate will work on modern, scalable payment solutions while contributing to the adoption and integration of Generative AI and LLM-based capabilities into enterprise applications. Key Responsibilities Design, develop, and maintain scalable applications using Java and Spring Boot.Develop and integrate REST APIs and microservices for payment-related platforms.Work closely with product, architecture, engineering, and business teams to deliver high-quality solutions.Contribute to the design and implementation of Gen AI / LLM-based solutions within enterprise applications.Explore and integrate AI capabilities such as LLMs, RAG, prompt engineering, AI agents, and intelligent automation where applicable.Develop secure and reliable solutions for payment processing and financial transactions.Analyse and troubleshoot complex technical and production issues.Ensure applications meet requirements for performance, scalability, security, and reliability.Participate in architecture and technical design discussions.Follow Agile development practices, including sprint planning, refinement, reviews, and retrospectives.Contribute to code reviews, automated testing, CI/CD, and continuous improvement initiatives.Required Skills & Experience Core Technical Skills 8+ years of professional software development experience.Strong hands-on experience with Java.Strong experience with Spring / Spring Boot.Good understanding of Microservices architecture.Experience developing and integrating REST APIs.Strong understanding of object-oriented programming and software engineering principles.Experience with relational and/or NoSQL databases.Experience with Git, CI/CD and modern software development practices.Generative AI Practical exposure to Generative AI / Large Language Models (LLMs).Understanding of LLM integration and AI-enabled application development.Exposure to technologies such as:RAG (Retrieval-Augmented Generation)Prompt EngineeringAI Agents / Agentic AIVector DatabasesLLM APIsAI application frameworksAbility to identify opportunities where Gen AI can improve business processes and application capabilities.Payments Domain Hands-on experience in Payments is mandatory.Understanding of payment processing and transaction flows.Experience working with payment platforms, payment services, or financial transaction systems.Knowledge of areas such as payment gateways, transaction processing, payment APIs, reconciliation, settlement, or fraud/security will be beneficial.Experience within Banking / Financial Services / FinTech environments is preferred.Soft Skills Strong analytical and problem-solving abilities.Excellent communication and collaboration skills.Ability to work effectively with distributed and cross-functional teams.Strong ownership and accountability.Ability to work in a fast-paced Agile engineering environment.Good understanding of software development best practices.Preferred Qualifications Experience working in large-scale enterprise or banking environments.Cloud experience with AWS, Azure, or GCP.Experience with Kafka or other event-streaming technologies.Knowledge of containerisation technologies such as Docker and Kubernetes.Experience implementing AI/Gen AI solutions in production environments.. Key Skills: Java | Spring Boot | Microservices | Gen AI | LLM | RAG | Payments | Banking | REST APIs | Cloud | Kafka