SmartCore is a fintech holding building 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.

Aunque la experiencia profesional y las cualificaciones son principal para este puesto, asegúrese de comprobar si posee las habilidades interpersonales preferibles antes de solicitar, si se requieren.

We are a leading fintech company developing innovative solutions in payment processing and anti-fraud technologies. We create high-tech products that are reshaping the financial landscape and are looking for true professionals ready to tackle complex and ambitious challenges.

About the Project:

You'll join a key team responsible for developing and evolving our core acquiring platform - a complex, high-load, microservices-based system operating 24/7. We handle the entire payment lifecycle, from initiation to clearing, ensuring minimal latency, high fault tolerance, and full compliance with strict security standards (PCI DSS).

What You'll Do:

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- Design and develop new microservices and business logic using Kotlin and Java.

- Optimize the performance of existing system components and handle high-load areas of the codebase.

- Make key architectural decisions aimed at improving fault tolerance, scalability, and platform security.

- Integrate with third-party payment systems, banks, and processing centers.

- Work with asynchronous data streams using Kafka and RabbitMQ.

- Conduct code reviews, mentor less experienced colleagues, and promote best development practices.

- Actively participate in R&D; - exploring and integrating new technologies into the project stack.

- Write unit and integration tests to maintain a high-quality codebase.

Our Ideal Candidate:

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- Has at least 10 years of commercial backend development experience with Java/Kotlin.

- Demonstrates expert-level proficiency in Kotlin: understands idioms, coroutines, functional features,



and applies them effectively.

- Possesses deep knowledge of Java Core and the JVM ecosystem.

- Has excellent command of Spring Boot - not only building REST APIs but also understanding its internals, auto-configuration, Spring Security, and Actuator.

- Expert in PostgreSQL - experienced in designing complex data schemas, optimizing queries, understanding transaction isolation levels, and replication mechanisms.

- Experience with MongoDB.

- Hands-on experience building systems with Kafka - understanding broker mechanics, producer/consumer patterns, and message delivery guarantees.

- Familiar with RabbitMQ and Redis (including caching, pub/sub, and distributed locks).

- Experience designing and building distributed, fault-tolerant systems (microservices architecture, CQRS, Event Sourcing).

- Comfortable with modern AI technologies, including AI agents, and capable of applying various LLMs in practice.

- Understanding of networking protocols (TCP/IP, HTTP/2, gRPC).

- Experience with containerization and orchestration tools (Docker, Kubernetes).

- Writes clean, maintainable, and well-tested code.

- Highly autonomous, proactive, and takes full ownership of product quality and outcomes.

- Fluent in Russian (B2 or higher) - required for daily communication within the team.

Nice to Have:

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- Experience in fintech or payment processing; familiarity with PCI DSS.

- Experience with reactive stacks (Project Reactor, WebFlux).

- Familiarity with monitoring and tracing tools (Prometheus, Grafana, Jaeger).

- Experience with load testing tools (JMeter, Gatling).

We Offer:

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- A competitive salary, discussed individually with each candidate.

- A modern technology stack and minimal bureaucracy.

- Budget for training, professional conferences, and books.

- Corporate access to all top-tier LLMs with maximum configurations.

- A team of passionate experts where your voice will always be heard. xcskxlj

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Hay opciones de teletrabajo/trabajo desde casa disponibles para este puesto.

📌 Senior kotlin/java (fintech) – remote friendly (emea)
🏢 SMARTCORE
📍 Barcelona