Java Backend Engineer

Java Backend EngineerRole SummaryWe’re looking for a hands-on Java backend engineer to design, build, and operate services that enable network-tokenized payments across Mastercard ecosystems: Click to Pay (SRC), Apple Pay, Google Pay, and Samsung Pay. You’ll integrate with Mastercard (MPGS/MDES), implement secure token lifecycle flows, and deliver high-availability APIs with strong security and compliance (PCI DSS).Key ResponsibilitiesDesign and develop backend services/APIs in Java (Spring Boot) for:Mastercard Click to Pay (SRC 2.x) enrollment, profile, cryptograms, and checkout orchestration.Wallet token flows for Apple Pay / Google Pay / Samsung Pay (tokenization, provisioning, PAN/D-PAN handling via MDES, cryptogram verification, payment token decryption/validation paths, when applicable).MPGS authorization/capture/refund/void flows and webhook/callback handlers.Implement network token lifecycle: provisioning, suspension, resume, PAN mapping, detokenization (where applicable) and card-on-file updates.Build merchant validation / domain association flows (e.g., Apple merchant validation, GPay gateway params), and manage SRC profiles.Implement robust security: JWE/JWS, JWT signing, HSM/TR-31 usage (or KMS alternatives), mTLS, key rotation, and secrets management.Ensure PCI DSS compliant logging, data minimization, and tokenized storage.Optimize service performance & scalability (caching, connection pools, async processing, idempotency keys, outbox pattern, retries, circuit breakers).Create CI/CD pipelines (GitLab + ArgoCD), IaC templates, and production run-books.Observability: structured logging, distributed tracing, metrics, dashboards, and alerts (SLOs/SLAs).Partner with frontend/mobile teams for Click to Pay UX and wallet checkout payload exchange contracts.Produce technical docs (API specs, sequence diagrams) and support audits/certifications.Must-Have SkillsJava 17+, Spring Boot, REST/gRPC, Gradle/Maven.Deep knowledge of payments: authorization flows, cryptograms (3DS2/CAVV/ECI), tokenization, PAN/D-PAN mapping, BIN ranges, merchant/acquirer concepts.Experience with Mastercard integrations (e.g., MPGS, MDES or issuer/acquirer rails).Practical know-how of Apple Pay / Google Pay / Samsung Pay server-side flows:Merchant validation (Apple) and payment token processing patterns.Google Pay/Samsung Pay gateway processing and payload verification.SRC (Click to Pay) concepts: SRCI, profiles, identity, EMVCo specs (high level).Security/crypto: JWE/JWS, JWT, mTLS, certificate pinning, KMS/HSM concepts, nonce/IV handling.Data stores: MySQL/PostgreSQL, schema design, indexes, query performance tuning.Messaging & patterns: Outbox, Idempotency, Retry/Backoff, Circuit Breaker.Cloud & containers: Docker, Kubernetes/GKE, GitLab CI, ArgoCD.Observability: OpenTelemetry, Prometheus/Grafana, log aggregation.Strong understanding of PCI DSS controls relevant to application development.Nice-to-HaveKotlin experience; familiarity with Go for perf-critical services.NATS/RabbitMQ/Kafka for async flows.Experience with MPGS features (3DS server integration, session IDs, token vaults).Knowledge of 3DS 2.2, SCA, risk-based authentication, and dispute flows.GCP stack: GKE Autopilot, Cloud SQL, Secret Manager, Cloud Armor, Pub/Sub.Caching: Redis; API gateways: Kong/Apigee.