infra-as-code, monitoring, alerting, and on-call runbooks for payment-critical systems. Optimize the data layer: schema design and query performance in MongoDB, caching and rate-limiting strategies with Redis, and safe migration patterns for high-volume transactional collections. Participate in on-call for payment-critical services, including incident … provider, or banking infrastructure strongly preferred . Strong hands-on expertise in Node.js (TypeScript preferred) for performant, production-grade backend services. Deep experience with MongoDB — schema design, aggregation pipelines, indexing strategy, and performance tuning at scale. Proficiency with Redis — caching, distributed locks, rate limiting, and pub/sub patterns. Proven ...