Senior Kotlin/Java Developer (Fintech)
REMOTE FROM EMEA
SmartCore is a fintech holding company creating infrastructure for the next generation of payments. Our solutions cover the entire financial operations cycle: from core banking and processing to cards, wallets, and anti-fraud systems.
About the project:
You will join a key team responsible for the development and evolution of our core acquiring platform. This is a complex, high-load system with a microservice architecture, operating 24/7. We are responsible for the entire payment lifecycle — from initiation to clearing, ensuring minimal latency, high fault tolerance, and compliance with strict security standards (PCI DSS).
Your responsibilities:
- Design and development of new microservices and business logic in Kotlin and Java.
- Performance optimization of existing system components, working with high-load code sections.
- Making key architectural decisions aimed at improving the platform's fault tolerance, scalability, and security.
- Integration with third-party payment systems, banks, and processing centers.
- Working with asynchronous data streams using Kafka and RabbitMQ.
- Conducting code reviews, mentoring less experienced colleagues, and implementing best development practices.
- Active participation in R&D, research, and implementation of new technologies into the project stack.
- Covering code with unit and integration tests, maintaining a high quality of the codebase.
Our ideal candidate:
- Has commercial backend development experience in Java/Kotlin for over 10 years.
- Expert knowledge of Kotlin: understands its idioms, coroutines, functional capabilities, and applies them in practice.
- Deep knowledge of Java Core and the JVM ecosystem.
- Excellent knowledge of Spring Boot: not only knows how to create REST APIs but also understands the framework's internal workings, principles of auto-configuration, Spring Security, Actuator.
- Expert level work with PostgreSQL: experience in designing complex data schemas, query optimization, understanding transaction isolation levels and replication mechanisms.
- Experience with MongoDB
- Practical experience building Kafka-based systems: understanding broker operating principles, producer/consumer patterns, message delivery guarantees.
- Experience with RabbitMQ and Redis (including caching, pub/sub, distributed locks).
- Experience in designing and developing distributed, fault-tolerant systems (microservice architecture, CQRS, Event Sourcing).
- Well-versed in modern AI technologies, including AI agents, and knows how to apply various LLMs in their work.
- Understanding of network protocol principles (TCP/IP, HTTP/2, gRPC).
- Experience with containerization and orchestration tools (Docker, Kubernetes).
- Habit of writing clean, maintainable, and well-testable code.
- Possesses a high degree of independence, is proactive, takes responsibility for the final result and product quality.
Will be a plus:
- Experience in fintech or payment processing, knowledge of the PCI DSS standard.
- Experience with reactive stacks (Project Reactor, WebFlux).
- Experience using monitoring and tracing tools (Prometheus, Grafana, Jaeger).
- Experience conducting load testing (JMeter, Gatling).
We offer:
- Competitive salary, discussed individually with each candidate.
- Modern technology stack and absence of bureaucracy.
- Budget for training, attending industry conferences, and purchasing literature.
- Corporate access to all advanced LLM models in the full configuration.
- Work in a team of passionate experts, where your opinion will always be heard.
To apply or clarify, you can contact directly: stanislav.pavlov@smartcore.pro
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