Senior Java Back-End Developer in Mississauga

We’re seeking a seasoned Senior Java Back-End Developer with 5+ years of experience to lead end-to-end technical design and delivery of mission‑critical systems. You will own architecture decisions, drive engineering excellence, mentor senior engineers, and partner with product, security, and platform teams to build scalable, reliable, and secure distributed systems.

Key Responsibilities

• Architecture & Design
  • Define and evolve system architecture for cloud-native, microservices/event-driven platforms (scalability, resilience, security, cost).
  • Create high-level and low-level designs, integration patterns, API contracts, and reference implementations.
  • Lead design reviews; ensure alignment with domain-driven design (DDD), 12‑factor principles, and organization standards.
• Engineering Leadership
  • Lead squads through full SDLC—from discovery and PoCs to production and SRE handoff.
  • Establish coding standards, code review practices, and secure‑by‑default patterns.
  • Mentor and coach senior engineers; support career growth and succession of technical leaders.
• Hands‑on Development
  • Build core services using Java (17+), Spring Boot, REST/GraphQL, and message/event streaming.
  • Optimize for performance, concurrency, observability, and operational excellence (SLOs, error budgets).
  • Drive quality with unit/integration/contract testing, test data strategy, and automated quality gates.
• Cloud & Platform
  • Design for AWS/Azure/GCP, container orchestration (Kubernetes), service mesh, and CI/CD.
  • Implement infrastructure‑as‑code (IaC) patterns and secrets management.
  • Partner with SRE/Platform teams on monitoring, alerting, logging, tracing, and cost governance.
• Data & Integration
  • Architect integrations across SQL/NoSQL, caching (Redis), and event streams (Kafka/Pulsar).
  • Define data contracts, schema evolution strategies, and idempotent/eventual consistency patterns.
• Security & Compliance
  • Embed AppSec best practices, OWASP controls, secure API/auth (OAuth2/OIDC), and zero trust patterns.
  • Ensure compliance with regulatory and audit requirements where applicable.
• Stakeholder Partnership
  • Translate business needs into technical roadmaps and architecture runway.
  • Communicate trade‑offs and decisions to both technical and non‑technical audiences.

Required Qualifications

• 5+ years of progressive experience building enterprise systems, with 5+ years in Java and Spring at scale.
• Proven delivery of cloud‑native, microservices, and event‑driven architectures.
• Strong expertise in: Java 11/17+, Spring Boot, Spring Cloud, REST/GraphQL APIs, gRPC (nice-to‑have), Kafka (or Pulsar), Kubernetes, Docker, RDBMS (PostgreSQL/MySQL/Oracle) and NoSQL (MongoDB/Cassandra/DynamoDB), Caching (Redis), CI/CD (GitHub Actions/Azure DevOps/Jenkins), IaC (Terraform/ARM), Observability (OpenTelemetry, Prometheus/Grafana, ELK), feature flags/progressive delivery.
• Solid grasp of concurrency, performance tuning, resiliency patterns (circuit breakers, retries, bulkheads), and fault‑tolerance.
• Demonstrated leadership of architectural forums, design reviews, and mentorship.
• Strong communication and stakeholder management skills.

Nice‑to‑Have

• Domain knowledge: Payments, banking, capital markets, insurance, e‑commerce, supply chain, or telecom.
• Security: Threat modeling, shift‑left security, SAST/DAST, secrets rotation, mTLS.
• Data: CDC (Debezium), schema registry, exactly‑once semantics, streaming ETL.
• Platform: Service mesh (Istio/Linkerd), API gateways (Kong/Apigee), Serverless (Lambda/Functions).
• Modern patterns: CQRS, event sourcing, Saga orchestration, hexagonal architecture.

Education

• Bachelor’s degree/University degree or equivalent experience.

Citi is an equal opportunity employer, and qualified candidates will receive consideration without regard to their race, color, religion, sex, sexual orientation, gender identity, national origin, disability, status as a protected veteran, or any other characteristic protected by law.