Michael Day

Michael Day met Ryan Cohen in an internet chat room focused on website design and computer programming when both were teenagers. Day became Chewy's Chief Technology Officer and was responsible for building the company's e-commerce platform, backend infrastructure, and technology architecture. His defining contribution was creating the technical foundation that enabled Chewy to scale from a three-person operation to a $12.6 billion revenue platform — including the inventory management system, order processing pipeline, and customer data platform that powered the Autoship subscription engine. Day's engineering leadership was instrumental in Chewy's ability to process millions of orders with 99.9%+ uptime.

Michael Day co-founded Chewy with Ryan Cohen in 2011 and served as the company's Chief Technology Officer. Day met Cohen in an internet chat room as a teenager, bonding over shared interests in website design and programming. While Cohen focused on customer service, brand, and investor relations, Day built the technical infrastructure that enabled Chewy's explosive growth. He architected the e-commerce platform from scratch, designed the inventory management system that supported the transition from third-party logistics to in-house fulfillment, and developed the data pipeline that powered Chewy's personalization and Autoship algorithms. Day's technical decisions — including the choice to build custom systems rather than rely on off-the-shelf e-commerce platforms — gave Chewy flexibility and scalability that competitors lacked. He remained with the company through the PetSmart acquisition and IPO, though he maintained a lower public profile than Cohen. Day's engineering culture emphasized reliability, speed, and data-driven decision-making — principles that continue to shape Chewy's technology organization.