Replatforming a $200M retailer without a minute of downtime.
Summit's decade-old commerce monolith buckled every holiday season. We modernized the platform in slices — strangling the legacy system piece by piece while revenue kept flowing through it.
Challenge
Summit's engineering team spent 70% of their time keeping the old platform alive. Page loads averaged six seconds on mobile, where 68% of their traffic lived. Every Black Friday was a war room. Leadership had two failed replatforming attempts behind them — both big-bang rewrites that collapsed under their own scope.
Approach
No big bang. We used a strangler pattern: the highest-revenue journeys — search, product page, checkout — were rebuilt first as independent services, routed gradually behind feature flags, and measured against the legacy paths before full cutover.
Solution
A modular commerce platform behind the same storefront customers already knew. Mobile pages render in under 1.8 seconds, the catalog scales for peak season without war rooms, and the team ships weekly instead of quarterly. The monolith was fully retired fourteen months in — and nobody outside the company noticed the transition.
Outcome
“Two rewrites failed before them. Gilva's plan was the first one that respected the fact that the store had to keep selling while we rebuilt it.”