Key challenges included stitching together multiple third-party healthcare APIs (ID verification, eRx, pharmacy logistics) and safeguarding large PHI datasets while keeping performance high. I solved these with layered caching, Next.js SSR for first-paint speed, background jobs/queues for long-running tasks, idempotent webhooks, and back-pressure controls. Deployed on AWS with a BAA, I implemented encryption in transit/at rest, secrets management, network isolation, and automated backups for reliability and scale.