Code Puppy creator leaves Walmart for Pydantic

Michael Pfaffenberger, the distinguished engineer who created Walmart’s internal vibe-coding tool Code Puppy, is leaving for AI start-up Pydantic after expanding the tool from 1,000 users to nearly 75,000. Walmart confirmed the departure and said the tool will continue to be supported by colleagues in its Global Tech group.

Code Puppy is based on the Pydantic AI library and helps users write, edit, test, and manage software through natural-language instructions. Walmart has said the tool is now used by about as many non-engineers as engineers, including hourly associates, with use cases spanning merchandising, supply chain, and store operations.

The tool is central to Walmart’s push to avoid dependence on a small set of AI providers. Unlike some rival coding assistants, Code Puppy can work with dozens of models from different suppliers, allowing users to compare outputs, switch providers, or distribute workloads to manage limits and costs. Pfaffenberger said the open source version has been downloaded over 496,000 times, including 71,000+ times last month, and will continue to be maintained by Walmart staff and outside contributors.