Walmart’s Code Puppy creator is leaving for Pydantic after 75,000 users
Michael Pfaffenberger, the distinguished engineer who built Walmart’s internal vibe-coding tool Code Puppy, is leaving the company to join AI startup Pydantic. He shared the news in a memo to colleagues reviewed by Business Insider.
A year ago, Code Puppy had roughly 1,000 users at Walmart. At the time of his departure, that number had grown to nearly 75,000, spanning engineers, store managers, supply chain teams, and hourly associates.
What Code Puppy Does
Code Puppy is built on the Pydantic AI library. It lets workers write, edit, test, and manage software through natural-language instructions, without needing to know how to code in the traditional sense. Walmart CTO Suresh Kumar described it in June as a way technology has been democratized across the organization.
One example: a regional load manager used Code Puppy to build a tool that analyzes hundreds of available truckloads to reduce empty-return trips for drivers. As of June, roughly half the user base is non-engineers.
Unlike Claude Code or OpenAI Codex, Code Puppy isn’t locked to a single AI provider. It can work with dozens of models, switch between them, compare outputs, and distribute workloads across providers to stay under usage limits and manage costs. That flexibility is a deliberate part of Walmart’s strategy to avoid dependency on a handful of AI suppliers.
The Open Source Numbers
Pfaffenberger’s decision to open source Code Puppy turned out to be a significant multiplier. The project has been downloaded more than 496,000 times, including over 71,000 times in the last month alone. More than 25 contributors submitted over 400 commits in the past month. The open source repository is at github.com/mpfaffenberger/code_puppy.
The project also attracted TJ Webb, who was an active open source contributor before Walmart hired him last month. Pfaffenberger and colleague John Choi received a direct award from CEO John Furner at Walmart’s annual shareholders meeting.
What Comes Next
Code Puppy is staying. A team of six will continue supporting and building the project: Ryan Eccles, John Choi, Kaveri Bakshi, Wesley Blakemore, Andrew Tilson, and TJ Webb. Pfaffenberger also published a set of written tenets for the project, derived from Sam Walton’s Made in America and Walmart’s core culture, to guide the team going forward.
At Pydantic, Pfaffenberger will focus on enterprise AI tooling, specifically the coordination of multiple agents. Pydantic CTO David Montague told Business Insider that this experience is critical as large companies work through the hard parts of AI adoption.
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