Senior Kotlin/Java Developer (Fintech) - remote friendly (EMEA)

Jordan martorell s.l.; España; A distancia; EUR 60.000 - 80.000; Jornada completa

Descripción de la vacante

A leading fintech company in Spain is seeking an experienced backend developer proficient in Kotlin and Java to join their team. You'll design and develop microservices while optimizing performance and ensuring system reliability. Candidates should have at least 10 years of experience, strong knowledge of Spring Boot, and fluency in Russian. Competitive salary and a modern tech stack offered.

Servicios

Competitive salary

Modern technology stack

Budget for training and conferences

Access to top-tier LLMs

Team collaboration and support

Formación

• At least 10 years of backend development experience.
• Expert-level proficiency in Kotlin.
• Knowledge of Java Core and JVM ecosystem.
• Excellent command of Spring Boot.
• Expert in PostgreSQL.
• Hands-on experience with Kafka.

Responsabilidades

• Design and develop new microservices using Kotlin and Java.
• Optimize performance of existing system components.
• Make architectural decisions for fault tolerance and scalability.
• Integrate with third-party payment systems and banks.
• Conduct code reviews and mentor less experienced colleagues.

Conocimientos

Backend development experience with Java/Kotlin

Expert-level proficiency in Kotlin

Deep knowledge of Java Core and JVM ecosystem

Excellent command of Spring Boot

Expert in PostgreSQL

Experience with MongoDB

Experience with Kafka

Familiar with RabbitMQ and Redis

Experience designing distributed systems

Comfortable with AI technologies

Understanding of networking protocols

Experience with Docker and Kubernetes

Writes clean and maintainable code

Fluent in Russian (B2 or higher)

Descripción del empleo

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.

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

• 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

• 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, 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

• 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

• 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.

Feel free to apply directly via LinkedIn or by sending your CV to stanislav. pavlov(@)smartcore. pro — if you’re ready for serious architectural challenges and want to build a product you can be proud of!