Challenge
The retailer's monolithic e-commerce application couldn't handle sudden traffic surges during flash sales and holiday events, resulting in checkout failures, cart abandonment, and lost revenue. Previous attempts to scale by simply adding servers were costly and only partially effective, since the bottlenecks were architectural, not just capacity-related.
Solution
Caystard decomposed the monolith into scalable microservices, introduced auto-scaling infrastructure with predictive load management, and implemented a caching and CDN strategy to offload static and semi-dynamic content. A new event-driven inventory system prevented overselling during traffic spikes.
Caystard began with load testing and architecture profiling to pinpoint exactly where the platform buckled under stress — primarily the checkout and inventory-lookup services. Rather than a full rewrite, we prioritized decoupling the highest-risk services (checkout, cart, inventory, and search) into independently scalable microservices, leaving lower-risk components on the existing stack for a faster, lower-risk rollout.
Auto-scaling policies were configured using historical and predictive traffic modeling, so infrastructure could scale up ahead of anticipated demand rather than reactively. A multi-layer caching strategy — combining CDN edge caching with in-memory application caching — reduced load on backend services by handling a large share of read-heavy traffic without hitting the database.
The new architecture was stress-tested against simulated Black Friday-level traffic several weeks before the real event, allowing the team to fine-tune scaling thresholds. During the actual peak season, the platform sustained a 10x traffic increase with no checkout downtime.