John Crepezzi

The Changing Craft of Programming

John Crepezzi, Ron

John Kripezzi now leads Jane Street's developer tooling and AI teams, where he pivoted the firm's strategy to build secure, internal LLM infrastructure shortly after ChatGPT's release. His initiatives, including the "Jane GPT" application and the "AIDMint" Slack system, have enabled over 1,000 tools and shifted 45% of released code through AI agent workflows while redefining security via distinct "AI Users" and adaptive allow-list models. This approach has fundamentally altered the engineering lifecycle by automating rote implementation tasks, forcing a human transition toward high-level design, adversarial security validation, and the verification of subtle AI-generated errors.