Senior Kotlin Backend Engineer

About us:

Paysera is an EU licensed e-money institution trusted by more than a million people worldwide. We make payments simple for e-commerce, retail, and everyday finances. With over 800 colleagues across the globe, we bring together fresh ideas and the stability of an international company. If you're curious, driven, and ready to grow with us in an AI-focused environment, Paysera is the place for you.

Role Overview:

• Title: Senior Kotlin Backend Engineer
• Level: Senior
• Reports To: Head of Backend Development
• Purpose: Build scalable payment APIs, design core banking services, and deliver robust integrations with third-party financial service providers.

Key Responsibilities:

• [R1] Design and implement scalable payment APIs using Kotlin and Spring Boot within the Paysera ecosystem.
• [R2] Develop and maintain RESTful APIs, microservices, and asynchronous workflows (Kafka/RabbitMQ)
• [R3] Design, implement, and optimize scalable data solutions, including relational databases, in-memory data stores, and search/analytics engines
• [R4] Apply Domain-Driven Design (DDD) and SOLID principles to model complex financial workflows and business rules.
• [R5] Implement ORM layers with Hibernate/JPA ensuring error rates below 1% and minimal query overhead.
• [R6] Build and execute automated test suites with JUnit/TestNG, maintaining ≥80% code coverage across services.
• [R7] Integrate Paysera backend with third-party financial systems, ensuring compliance with API specifications and security standards.
• [R8] Develop and maintain microservices supporting core banking services with a focus on reliability and latency under 200ms.
• [R9] Optimize database schemas and queries (PostgreSQL, MariaDB) for throughput exceeding 1,000 TPS.
• [R10] Debug and maintain distributed applications with observability tools (Sentry, Graylog, Grafana, Kibana).
• [R9] Champion AI-assisted engineering workflows (Claude Code, Cursor, etc.) to accelerate development while enforcing code quality.
• [R10] Mentor engineers, conduct code reviews, and contribute to RFCs to foster a culture of quality, security, and continuous learning.
• [R11] Participate in code reviews, mentoring, and RFCs to foster a culture of quality, security, and continuous learning.
• [R12] Collaborate with engineers, delivery managers, and product teams to ensure delivery of features aligned with business goals.

Must-Have Qualifications:

• [Q1] 5+ years of backend development experience in Java SE/EE and Kotlin, verified via CV and code samples.
• [Q2] 2+ years working in a team on complex, enterprise-grade projects
• [Q3] Experience with reactive programming (WebFlux, Kotlin Coroutines, R2DBC)
• [Q4] 5+ years of hands-on experience with Spring Framework (Spring Boot, Spring MVC, Spring Data), validated in interviews.
• [Q5] 5+ years of experience designing and delivering microservices with RESTful APIs in production environments.
• [Q6] Strong expertise in DDD, SOA, SOLID, and event-driven systems
• [Q7] 5+ years of database design and optimization experience with PostgreSQL or MariaDB, validated through SQL review tasks.
• [Q8] Proven track record using Hibernate/JPA for ORM with enterprise-scale applications.
• [Q9] 3+ years of experience with unit and integration testing frameworks (JUnit/TestNG), with portfolio evidence of coverage metrics.
• [Q10] Proficiency in OAuth2 / JWT authentication and secure API standards.
• [Q11] Understanding of PSR standards
• [Q12] Strong debugging skills and experience with monitoring tools (Sentry, Graylog, Grafana, Kibana)[Q13] Hands-on experience with Redis and ElasticSearch
• [Q14] Fluency in English — written and verbal.

Nice-to-Have:

• [N1] Experience with high-load, large-scale systems.
• [N2] Familiarity with Docker, Kubernetes, Helm, GitOps workflows.
• [N3] Hands-on experience with Kafka, RabbitMQ, event-driven architectures.
• [N4] Knowledge of additional programming languages (PHP, Golang, Python).
• [N5] Experience with SOAP/XML services in enterprise contexts.
• [N6] Exposure to front-end frameworks and e-commerce platforms.

Domain Expertise (Fintech Superpowers – Bonus Plus!):

• Core banking (multi-currency, payments, account management).
• Compliance (KYC/AML workflows, audit trails, sanctions screening, FATCA/CRS).
• Financial standards (SEPA, SWIFT, ISO20022, PSD2).
• Risk & Fraud prevention (transaction monitoring, anomaly detection, rule engines).
• Financial security (PCI-DSS, tokenization, key management).
• High-volume async processing (queues, batch jobs).
• E-commerce payments (card processing, payment gateways).

Work Conditions & Contract Info:

• [W1] Employment Type: Full-time, permanent contract.
• [W2] Location/Arrangement: Remote
• [W3] Core Hours: Business hours aligned with CET/EET.
• [W4] Compensation: Range TBD (provided by employer).
• [W5] Start Date: Immediate or upon notice period.

What we offer:

Work-life Balance: strive for balance with flexible working hours and full remote work possibilities.

Innovation and Development: participate in skill-building workshops and have freedom to experiment with various AI tools.

Growth-focused Culture: thrive within a highly professional, quality-oriented, and dynamic team and pursue your potential and innovative ideas in a fast-growing, international company.

For candidates:

Only selected candidates will be contacted, but we are grateful to all who send their CV.