Fullstack Engineer

Senior Java Microservices Engineer – Payments (IKP | Service Mesh)

Contract Role | Long-Term Engagement

Role Purpose

We are looking for a Senior Java Microservices Engineer to design and build high-throughput, low-latency payment systems. You will develop scalable, secure, and resilient microservices on a Kubernetes-based platform (IKP), leveraging Service Mesh capabilities to enable reliable service-to-service communication.

This role is critical in delivering modern, event-driven payment solutions supporting key journeys such as payment initiation, validation, routing, clearing/settlement, and exception handling.

Contract & Working Model

• Contract Type: Long-term contract engagement
• Work Model: Hybrid
• Location: Kraków, Poland
• Office Requirement: Approximately 6 days per month onsite

Key Responsibilities

• Design, develop, and maintain Java-based microservices for payment processing and orchestration
• Build and expose REST and gRPC APIs for internal and external integrations
• Develop event-driven services using messaging platforms such as Kafka
• Implement resilience patterns including retries, timeouts, circuit breakers, and bulkheads
• Leverage Service Mesh capabilities (traffic routing, mTLS, observability, policy enforcement)
• Ensure systems are designed for high performance and scalability (low latency, high throughput, concurrency control)
• Implement idempotency and safe retry mechanisms for reliable payment processing
• Apply payments-grade controls including auditability, traceability, and non-repudiation
• Collaborate with product, architecture, and SRE teams to deliver secure and scalable services
• Drive engineering best practices including code reviews, automated testing, and CI/CD pipelines
• Support production systems, including incident management and post-mortems

Required Technical Skills

• Strong hands-on experience with Java (modern versions)
• Proven experience building microservices architectures
• Experience with Kubernetes-based platforms (IKP or equivalent)
• Strong understanding of Service Mesh concepts (e.g., Istio, Linkerd, Envoy)
• Experience with event-driven architecture and messaging systems (e.g., Kafka)
• Solid knowledge of API design (REST, gRPC, OpenAPI)
• Experience implementing resilience and fault-tolerance patterns
• Understanding of observability practices (distributed tracing, metrics, logging, OpenTelemetry)
• Experience with CI/CD pipelines and automated testing

Preferred / Nice-to-Have

• Frameworks: Spring Boot or Quarkus
• Build tools: Maven or Gradle
• Containers & orchestration: Docker, Kubernetes
• API tools: Swagger/OpenAPI, API Gateways
• Security: OAuth2, OIDC, JWT, mTLS, secrets management
• Testing: Unit, integration, contract testing (e.g., Pact), performance testing
• Experience with SAST/DAST tools

Payments Domain Experience

• Strong understanding of payment processing flows (STP, validation, routing, reconciliation)
• Familiarity with payment standards and rails such as:
• ISO 20022
• SEPA
• Faster Payments
• ACH
• Knowledge of risk and compliance controls:
• Transaction limits
• Sanctions screening touchpoints
• Audit trails and regulatory requirements