Senior Java Developer

Senior Java Developer (Payments & AI Solutions)

Location: 100% Remote
Cooperation model: B2B / Full-time
Rate: 150-170 PLN net

About the project

Join a team developing a modern payment platform handling thousands of transactions in a high-availability, large-scale environment. We are looking for an experienced Senior Java Developer responsible for designing and developing key backend services, payment integrations, and solutions based on microservices architecture. Interest in using AI/LLM technologies in products and business processes is an additional advantage.

Responsibilities

• Design, development, and maintenance of backend applications in Java.
• Creation and development of microservices architecture.
• Building and integrating REST APIs with internal and external systems.
• Implementation of asynchronous communication solutions (Kafka or RabbitMQ).
• Collaboration with product teams, architects, and DevOps.
• Ensuring high code quality, security, and system performance.
• Participation in designing payment processing and data security solutions.

Requirements

Must-have

• Minimum 5 years of backend programming experience in Java.
• Very good knowledge of Java 17+ (Java 21 is a strong plus).
• Practical experience with Spring Boot and Spring ecosystem (Security, Data, WebFlux or MVC).
• Experience in designing and maintaining distributed systems and microservices.
• Knowledge of message brokers: Kafka or RabbitMQ.
• Very good knowledge of PostgreSQL and SQL.
• Experience in designing and integrating REST APIs.
• Practical knowledge of cloud environments (AWS or GCP).
• Experience with Docker and Kubernetes.
• Knowledge of security topics in payments, including PCI-DSS, data encryption at rest and in transit, token management, and sensitive data handling.

Nice to have

• Experience in fintech, payments, or e-commerce.
• Practical use of LLM model APIs (OpenAI, Anthropic or similar).
• Knowledge of AI Agents, RAG, prompt engineering, and tool-use.
• Knowledge of PSD2, PCI-DSS, or ISO 8583 standard.
• Experience in building or integrating payment widgets and SDKs for merchants.

We offer

• Participation in building modern large-scale financial products.
• Influence on architecture and technological decisions.
• Work with the latest Java and Cloud technologies.
• Opportunity to develop in AI and modern LLM-based solutions.
• Flexible cooperation model and friendly work environment.
• Long-term project delivered by an experienced team of experts.

Benefits

• Multisport card and Luxmed.