Senior Java Engineer

About the Role

We're looking for a Senior Java Engineer to lead the integration and enhancement of a recently acquired Payment Hub into our existing payments platform — ~232 PSP integrations, a cashier tier, and a set of core services running on EKS (AWS eu-central-1, ARM64) with GCP as a secondary region. You'll architect and build high-throughput backend services on modern Java and Spring Boot 3.x, onboard and mentor mid- and junior-level engineers, drive engineering standards, and partner with DevOps and Architects to deliver scalable, fault-tolerant solutions under real payment SLAs.

What We're Looking For

• 5+ years of backend Java experience; we run mostly Java 23 with newer services on Java 25, so fluency in modern Java (17+) is required.
• Production experience with Spring Boot 3.x, Spring Cloud, and the wider Spring ecosystem (Security, Data, OpenFeign, Actuator).
• Hands-on Apache Camel for EAI/integration — route design, DSL, and operating Camel under load (this is the integration backbone for our PSP tier).
• Experience with reactive Java — Spring WebFlux + Project Reactor + R2DBC — on latency-sensitive paths.
• Strong PostgreSQL skills with JPA/Hibernate (and ideally R2DBC), schema migrations via Liquibase.
• Kafka at scale — consumer-group design, delivery semantics, partition and rebalance tuning (AWS MSK or equivalent).
• Redis for caching, idempotency keys, and distributed locks (ShedLock or similar).
• Microservices, REST, OpenAPI-driven contracts, Maven build pipeline.
• Keycloak / OAuth2 / OIDC; secret management with Vault, External Secrets, or AWS Secrets Manager.
• Production AWS experience: EKS, MSK, RDS, ElastiCache, S3, CloudWatch, IAM/IRSA.
• Working knowledge of Docker, Kubernetes, Helm, and CI/CD (GitLab CI ideally).
• Solid grasp of high-load, fault-tolerant system design — circuit breaking, retries, back-pressure, p99 latency reasoning, capacity planning.
• Understanding of payment and financial systems.
• Strong communication, mentoring, and technical leadership skills.

Nice to Have

• Drools / DRL / decision tables (KIE Server experience a bonus) — used for routing, fraud/AML, and merchant-specific rules.
• OpenSearch for search and audit trails.
• Service mesh (Istio) and progressive delivery (Flagger / canary releases).
• Observability stack: Micrometer, Prometheus / VictoriaMetrics, Grafana, Datadog, OpenTelemetry.
• Infrastructure as Code with Terraform / Terragrunt.
• GitOps with Flux CD v2 and Helm.
• ARM64 / Graviton workloads, Karpenter-based autoscaling.
• AWS networking (VPC, Route 53, ELB) and security best practices.

What You'll Do

• Lead the design, development, and maintenance of Java microservices across the payments platform.
• Integrate and extend the new Payment Hub into our existing ecosystem.
• Drive code review, architectural decisions, and continuous improvement.
• Onboard and mentor junior and mid-level engineers — pair on real work, give thorough reviews, and help them level up.
• Champion best engineering practices: Testcontainers-first testing, observability, performance, secure coding, clean architecture.
• Run and present internal tech talks and share learnings across the team.
• Collaborate closely with DevOps on CI/CD, containerization, and infrastructure provisioning.
• Participate in on-call rotation for the services you own.

We Offer

• Fully remote work with a flexible schedule
• Paid sick leave and vacation
• Thoughtful gifts for holidays and personal milestones
• All equipment you need to do your job well
• Internal events: open discussions, product meetups, and soft-skills training
• Flat structure, no micromanagement, fast decision-making