Java Backend Engineer (Card Payment)
First seen by Alion on Nov 5, 2026.
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