The creator of Walmart’s internal vibe-coding tool is leaving the company for AI start-up Pydantic.
In a memo reviewed by Business Insider, Michael Pfaffenberger wrote to colleagues that he was leaving Walmart a year after growing Code Puppy from 1,000 users to more than 75,000. The tool will continue to be supported by his colleagues at Walmart.
Code Puppy, based on the Pydantic AI library, was created by Pfaffenberger, a distinguished engineer in Walmart’s Global Tech group. The AI coding assistant helps developers write, edit, test, and manage software using natural-language instructions.
“I’m filled with joy that I was able to create software that improved the lives of so many folks at work and outside of it,” Pfaffenberger wrote in the memo. “These decisions are never easy, but the time is right.”
Walmart confirmed Pfaffenberger’s departure and wished him the best. The company is in a quiet period ahead of its earnings report on August 20.
“People are using it in merchandising, people are using it in supply chain, store managers are using it. It’s a way where the power of technology has now gotten democratized,” chief technology officer Suresh Kumar said in June.
The company said in June that Code Puppy is now used by about as many non-engineers as there are engineers, all the way to hourly associates. One regional load manager used Code Puppy to design a tool that analyzes hundreds of available truckloads in the region to minimize truck drivers turning around after a dropoff without a load.
Code Puppy is part of Walmart’s effort to avoid what many technology executives fear could become one of the defining business problems of the AI era: getting locked into a handful of powerful providers.
Like Anthropic’s Claude Code and OpenAI’s Codex, it can build features, fix bugs, and analyze projects. But unlike many rivals, Code Puppy isn’t tied to a single AI model or provider.
Instead, it can work with dozens of models from different suppliers, allowing developers to switch between them, compare results, or use several at once. It can also distribute workloads across providers, helping avoid usage limits and control costs.
Walmart already has a dizzying number of agents and a handful of super-agents tailored for particular use cases, but Code Puppy was notable for its ability to help people across the organization vibe code their own solutions.
At the annual shareholders meeting last month, Pfaffenberger and his colleague John Choi received an award from CEO John Furner in recognition of the project.
Pydantic chief technology officer David Montague told Business Insider that Pfaffenberger is bringing his unique experience at a large enterprise building AI tools that coordinate multiple agents. This is a critical skill as large companies struggle with AI adoption, he added.
Read Pfaffenberger’s memo to staff
Code Puppy is Staying
Friends, Walmartians, Vibe Coders,
A year ago today, Code Puppy barely had 1,000 total users. Now our lifetime user count, at the time of writing this email, is approaching 75,000. I’m filled with joy that I was able to create software that improved the lives of so many folks at work and outside of it.
This was not easy. I poured my soul into it for the past year. You kept me motivated. All of you, the users who felt empowered by the tool that I created, have been my lifeline and the reason I’ve kept going for so long.
Unfortunately, the time has come for me to say goodbye. These decisions are never easy, but the time is right.
With Brian Knapp’s blessing, I was able to build a wonderful team. In my absence, these amazing folks will continue supporting and building on this project:
- Ryan Eccles – Associate Fellow II
- John Choi – Principal Software Engineer
- Kaveri Bakshi – Director, Technical Program Management
- Wesley Blakemore – Senior Software Engineer
- Andrew Tilson – Principal Software Engineer
- TJ Webb – Principal Software Engineer
Read more about them here: puppy.walmart.com/team
Together, they will uphold the tenets written here (puppy.walmart.com/tenets) and keep the project alive and well. I wrote these tenets recently, knowing that I would be gone soon. They are derived from the lessons in Made in America by Sam Walton, as well as the fundamental core of Walmart culture itself. Every team should follow them, not just this one.
And now that the team is up and running, I must say goodbye.
The decision to open source Code Puppy was pivotal. Code Puppy has been downloaded on the open source over 496,000 times, including 71,000+ times last month, by users all over the world. Dozens of individuals unaffiliated with Walmart have contributed powerful features and bug fixes. Because of this, it was almost like I had an entire team of elite software engineers – some of them folks at the absolute top of their fields, coming out of Stanford, like Qian Li (Founder of DBOS).
In September and October of last year, open source Code Puppy became heavily used in the Cerebras Discord when they launched their inference product. TJ Webb, a recent addition to the team, was one of those users. TJ has been contributing to Code Puppy the entire time – we just hired TJ last month.
github.com/mpfaffenberger/code_puppy is the open source version. You can use it on your machine at home. Do not use this version at Walmart, it won’t work. Always use the internal one.
But please consider giving it a star on GitHub. This will attract more developers to maintain it when I’m gone.
And so here is my final release inside of Walmart, a culmination of over ~25 contributors and over 400 commits over the past month. Release notes below.
With gratitude, and bark mode activated one last time, thanks to all of you, sincerely, from the bottom of my heart,
Michael Pfaffenberger
Creator, Code Puppy
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