Overseas Contractor- Senior Backend developer
Confirmed on the employer's own hiring board on Oct 17, 2026. First seen by Alion on Oct 1, 2026. Ltm scores B on the Alion truth index.
Role-Senior Java Backend Developer- Payments AI Enabled Spec Driven Development
Location Gdynia and Warsaw Poland- hybrid client site
Hiring- B2B/ Subcon
Experience- 10 years in Java backend development including 5 years in payments or banking
Role Summary
We are looking for a senior Java backend developer with hands on payments experience to design and build secure high performance payment services The candidate should be expert in Core Java Spring Boot microservices and Kafka They should also use AIassisted engineering especially spec driven development to deliver high-quality software faster Working directly with Nordic client stakeholders they will own solutions from specification through to production
Key Responsibilities
Design develop and maintain scalable payment microservices for payment initiation clearing settlement and reconciliation
Build eventdriven high throughput flows using Kafka with idempotency exactly once handling and reliable retry and error handling
Write clear specifications requirements acceptance criteria API contracts data models and use them as the single source of truth for AIassisted design code generation and testing
Use AI coding assistants and agents eg GitHub Copilot Spec Kit or similar to turn specifications into plans tasks code and tests Critically review all AIgenerated output for correctness security and compliance
Design REST APIs contract first using OpenAPI and keep specifications and code in sync
Make sure solutions meet banking grade standards for security resilience audit and data protection
Work with product owners architects and testers in Agile SAFe teams Mentor other developers on modern Java and AIassisted engineering practices
Support production and analyse incidents for business critical payment systems
Required Skills
Java and backend
Expert in Java 17 Java 21 preferred Spring Boot 3 Spring Framework Spring Data Hibernate JPA
Spring Security with OAuth2OIDC JWT and mTLS
Microservices patterns API gateway circuit breaker saga outbox CQRS and event sourcing
Kafka producers consumers partitioning schema registry Kafka Streams
Contractfirst REST API development OpenAPISwagger API versioning and documentation
Payments domain
Handson experience with ISO 20022 messages pain pacs camt and SWIFT MTMX migration
Knowledge of SEPA Credit Transfer SEPA Instant SCT Inst SEPA Direct Debit and realtime payment schemes such as TIPSRT1
Understanding of the payment lifecycle initiation validation screening routing clearing settlement and reconciliation
Awareness of EU regulation including PSD2Open Banking APIs the EU Instant Payments Regulation DORA GDPR and AMLsanctions screening
AI and specdriven development
Practical experience with specdriven development writing structured testable specifications that drive AIgenerated design code and tests
Skilled use of AI coding assistants and agents in daily development prompt and context engineering iterating on output generating tests
Ability to validate AIgenerated code for quality security and performance and to apply guardrails such as code review static analysis and policy checks
Understanding of responsible AI in regulated environments no sensitive data in prompts traceability human oversight
Data and databases
Strong relational database skills Oracle MS SQL PostgreSQL complex queries performance tuning transactions and locking
Database migration tools Flyway Liquibase
DevOps and quality
Docker and Kubernetes OpenShift a plus
CICD Git Maven BambooJenkinsGitHub Actions Ansible artifact repositories Nexus Artifactory
Testing JUnit 5 Mockito Testcontainers contract testing Pact Spring Cloud Contract performance testing
Code quality and security SonarQube static and dependency security scanning SASTSCA OWASP Top 10
Shell scripting and scheduling tools UC4Automic AutoSys ControlM
Ways of working
Experience in Agile and SAFe delivery
Good to Have
Cloud platforms Azure AWS GCP
Observability Grafana Prometheus OpenTelemetry AppDynamics ELKSplunk
Experience with Nordic banks or payment providers
Older stacks for maintenance work WebLogic Tomcat JSP JavaScript Bootstrap
Certifications Oracle Java Spring Professional Kubernetes CKAD cloud certifications