Java Backend Engineer with Gen AI

Thrive IT Systems; Warszawa; Hybrid; PLN 180,000 - 320,000; Full time

Job summary

Thrive IT Systems in Poland is seeking a Senior Java Backend Developer with payments domain experience to design and build secure, high-performance payment services. You will be expert in Core Java, Spring Boot microservices and Kafka, and will apply AI-assisted spec-driven development to deliver quality software.

You'll work directly with Nordic client stakeholders in a hybrid setup (Gdynia and Warsaw), owning solutions from specification through to production while mentoring peers in modern

Qualifications

• Must have extensive Java backend experience, with payments domain
• Proficient in Spring Boot, microservices, and Kafka
• Experience with AI-assisted engineering and spec-driven development
• Strong API design using OpenAPI/Swagger
• Knowledge of ISO 20022, SWIFT, SEPA and real-time payment schemes
• Experience in Agile SAFe environments

Responsibilities

• Design, develop, and maintain scalable payment microservices
• Build and manage high-throughput event-driven flows using Kafka
• Write specifications and acceptance criteria to drive AI-assisted design
• Review AI-generated output for security and correctness
• Design REST APIs contract-first using OpenAPI
• Ensure banking-grade security and data protection
• Collaborate with product owners, architects, and testers in SAFe teams; mentor others
• Support production and analyze incidents in payment systems

Skills

Core Java

Spring Boot

Microservices

Kafka

OpenAPI

OAuth2/OIDC

Security

Data modeling

AI-assisted development

SAFe Agile

Tools

Docker

Kubernetes

Git

Maven

CI/CD

OpenShift

GitHub Actions

Nexus

Ansible

Job description

Role: Senior Java Backend Developer- Payments AI Enabled Spec Driven Development

Location: Gdynia and Warsaw, Poland

Hybrid - 3 Days

Extensive years in Java backend development including hands on 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 AI-assisted 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 event-driven 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 AI-assisted 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 AI-generated 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 AI-assisted engineering practices
• Support production and analyze incidents for business-critical payment systems

Required Skills

Java and backend

• 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
• 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 real-time 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 spec-driven development writing structured testable specifications that drive AI-generated 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 AI-generated 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
• DevOps and quality
• Docker and Kubernetes OpenShift a plus
• CICD Git Maven Bamboo Jenkins GitHub Actions Ansible artifact repositories Nexus Artifactory
• Testing JUnit 5 Mockito Test containers 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

• Observability Grafana Prometheus OpenTelemetry AppDynamics ELK Splunk
• Experience with Nordic banks or payment providers
• Certifications Oracle Java Spring Professional Kubernetes CKAD cloud certifications

Skills