Simon Willison is a prolific independent software developer, a blogger, and one of the most visible and trusted voices on the impact AI is having on builders. He co-created Django, the web framework that powers Instagram, Pinterest, and tens of thousands of other websites. He coined the term “prompt injection,” popularized the terms “AI slop” and “agentic engineering,” and has built over 100 open source projects, including Datasette, a data analysis tool used by investigative journalists worldwide. What makes Simon unique is that he’s made the leap from traditional software engineering to AI-native development more fully and visibly than almost anyone—and he’s been documenting everything he learns in real time on his blog, SimonWillison.net.

In our in-depth conversation, Simon shares: 1. Why November 2025 was the inflection point when AI coding agents crossed from “mostly works” to “actually works” 2. How Simon writes 95% of his code from his phone now and why he’s mentally exhausted by 11 a.m. 3. Why mid-career engineers (not juniors) are most at risk right now 4. The three agentic engineering patterns Simon uses daily (red/green TDD, templates, hoarding) 5. The next leap: the “dark factory” pattern where nobody writes or reviews code and AI does its own QA 6. Why prompt injection is an unsolved security problem and the “lethal trifecta” that will likely lead to an AI Challenger disaster 7. Why the pelican riding a bicycle became the unofficial benchmark for AI model quality — Brought to you by: WorkOS—Modern identity platform for B2B SaaS, free up to 1 million MAUs Vanta—automate compliance, manage risk, and accelerate trust with AI — Episode transcript: lennysnewsletter.com/p/an-ai-st… — Archive of all Lenny's Podcast transcripts: dropbox.com/scl/fo/yxi4s2w998p1… — Where to find Simon Willison: • X: x.com/simonw • LinkedIn: linkedin.com/in/simonwillison • Website: • Agentic Engineering Patterns: — Where to find Lenny: • Newsletter: • X: • LinkedIn: — In this episode, we cover: — References: — Production and marketing by . For inquiries about sponsoring the podcast, email podcast@lennyrachitsky.com. — Lenny may be an investor in the companies discussed.