Java Backend Engineer (Card Payment)

About the project

Our client is a fintech company building a new digital banking and payments product from scratch. You will join the team building its card issuing platform (issuer processing): real-time card authorisation, clearing and settlement, and integrations with the card scheme, a banking partner and payment providers.

The product is at an early stage: architecture, team and roadmap are being shaped now, and the scope will be refined together with the team. You will join a mixed team of client and NerdySoft engineers. AI-assisted development is part of everyday engineering.

What you will do

• Design, build and ship Java services of a new card processing platform
• Implement card transaction flows: authorisation, reversals, refunds, clearing and settlement - correct and idempotent at money level
• Build reliable integrations with the card scheme, banking partner and payment providers - traceable and easy to reconcile
• Own the technical design of features and components, and contribute to architecture decisions together with the Tech Lead
• Keep the bar for quality: code reviews, testing standards, performance, reliability and security (PCI DSS)
• Work with AI coding assistants and AI agents in daily development: delegate tasks to agents, review the code they produce and keep it to the team's standards for review and testing
• Support features in production: monitoring, incident analysis, fixes
• Mentor middle engineers; clarify requirements and discuss technical solutions directly with client stakeholders

What you bring

• 5+ years of commercial backend development with Java (17+) and Spring Boot
• Commercial experience in card payments, issuing side preferred: card issuing or issuer processing, acquiring, payment gateways / PSPs or card scheme integrations
• Production experience with high-load, transactional, event-driven systems (Kafka, RabbitMQ, AWS SNS/SQS or similar)
• Solid knowledge of concurrency and transactions: ACID, isolation levels, optimistic and pessimistic locking, idempotency
• Strong PostgreSQL (or other relational DB) skills: schema design, query optimisation, JPA / Hibernate
• Integrations with external providers: retries, timeouts, reconciliation, consistent error handling
• Strong testing culture: unit, integration and contract tests (JUnit, Mockito, Testcontainers)
• Docker, CI/CD and hands-on AWS (or another major cloud)
• Daily use of AI coding assistants and agents (Claude Code, Cursor, GitHub Copilot or similar): you can show how they speed you up and how you check their output
• English B2+ (Upper-Intermediate or higher): you will discuss technical solutions directly with the client

Nice to have

• Issuer processing: ISO 8583, authorisation, clearing and settlement files, chargebacks
• Visa or Mastercard integrations and scheme certification
• Tokenisation for digital wallets, 3DS
• PCI DSS in practice; HSM and key management
• Ledger systems and double-entry accounting
• Kotlin or Scala; DDD, Clean or Hexagonal architecture; Kubernetes, Terraform

What we offer

• Comfortable workplace and modern office facilities
• Flexible working hours with no overtime and the ability to work remotely
• 50% compensation for certifications, conferences, training
• 50% compensation for English courses
• 18 working days of paid annual leave
• Paid sick leave
• Medical insurance and sports compensation