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Case study · Retail
A top-100 D2C retailer's Magento monolith was at the limit of what could be patched into Black Friday survival. We replatformed onto a headless commerce architecture in 7 months with a peak-season-tested cutover, then walked the operations team through a Black Friday that delivered 8x peak-traffic capacity with no degradation.
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The challenge
The customer's Magento 2 estate had been patched, partially extended, and operationally stretched across four years. Page-load times were degrading; peak-season scaling had become a quarterly engineering sprint; and the third-party extensions in production had divergent fates as Magento's roadmap evolved. The retailer's BFCM week represented 18% of annual revenue. An outage during peak was an existential question for the engineering org.
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Our approach
We replatformed onto a headless architecture: Next.js storefront on Vercel, commercetools for the commerce platform, Algolia for product search, Stripe for payments, and a custom read-model layer on Postgres + Redis that decoupled storefront reads from the commerce platform's transactional load.
The read-model layer was the architectural bet. Storefront pages render from a denormalized Postgres + Redis cache that's continuously updated from commercetools events. Commerce platform load is bounded by writes (carts, checkouts). Read traffic doesn't touch it. This is what made 8x peak capacity defensible.
Six weeks before BFCM, we ran chaos-engineering exercises against the staging environment scaled to peak load: random pod kills, AZ failover, CDN edge degradation, payment provider latency injection, third-party extension timeouts. Every failure mode the post-mortem corpus documented got rehearsed.
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The solution
Phased cutover by category and traffic source, with documented rollback per phase. New architecture in front of CDN edge cache (Vercel + Cloudflare); legacy Magento served as fallback during cutover windows. Twelve cutover phases over 6 weeks; each gated on conversion-rate parity vs the legacy baseline.
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Results
BFCM week shipped on the new platform with zero P0 / P1 incidents. Peak traffic was 8x the prior year; conversion rate held parity through peak; median page load fell 47%. Engineering on-call received zero pages during the peak Saturday window. The war room sat in calm tension and watched the dashboards do their job.
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