Nitin Anand

Multi-tenant digital signature SaaS — PHP → Java Spring Boot migration with enterprise auth.

• Built multi-tenant architecture with isolated tenant context, independent auth configs, and org-level data separation.
• OAuth2/OIDC via Keycloak (SSO, passkey); parallel I/O for document signing achieving sub-second latency at load.
• eIDAS & XAdES standards compliance, ASiC-E container generation, and API key management for third-party integrations.

Event-driven reward engine serving 100K+ daily users with 1M+ evaluations per day.

• Designed fault-tolerant microservice architecture with efficient reward computation and state machine management.
• Kafka-based async reward processing decoupling reward triggers from evaluation — zero user-facing latency.
• Idempotent reward grant logic with distributed locks to prevent duplicate reward issuance under retries.

Scalable multi-channel notification delivery — SMS, Push, WhatsApp — at millions per day.

• Decoupled producer/consumer model on Kafka; each channel as independent consumer group for isolated scaling.
• Quartz-based retry scheduler with exponential backoff and DLQ routing for failed delivery — >99% on-time rate.
• Slack webhook alerting for scheduler failure monitoring with AWS Lambda for serverless DLQ processing.

Real-time market data processing at 5K–10K ticks/sec in a trading system.

• Multithreaded JAX-RS/Spring Boot services with thread pool tuning and lock-free data structures for low-latency reads.
• Redis caching layer for hot market data — 40%+ reduction in DB hits, 25–30% latency improvement under peak load.
• PostgreSQL query optimization (stored procedures, index tuning); migrated legacy batch jobs to parallel ETL with Talend.

Dynamic configuration microservice pulling from S3 and routing to Kafka topics.

• Service reads JSON config files from S3 on startup/refresh — no redeploy needed for topic routing changes.
• Event-driven routing: config-driven Kafka topic fanout with partition assignment and consumer group management.
• Spring Boot actuator health checks + S3 config caching with TTL-based invalidation.

Production-grade email service with HTML templates, multi-file attachments, and SMTP.

• Templating engine for dynamic HTML email generation — per-event template resolution with variable injection.
• Async send with retry queue; SMTP error classification (transient vs. permanent) for retry eligibility.
• REST API with request validation and rate-limiting to prevent abuse in multi-tenant deployments.