How We Built 23 Websites in 48 Hours with AI Agents

This is not a thought experiment. In March 2026, a single developer and a team of eight Claude Code agents built and deployed 23 production utility websites in 48 hours. No templates-as-a-service. No landing page clones. Real tools — a paycheck calculator that handles all 50 US states, fitness calculators using validated medical formulas, PDF tools that process files entirely in the browser. Here's exactly how we did it. The Problem The internet is full of utility websites that are either plastered with ads, painfully slow, or both. Try to calculate your paycheck withholding? You get a page that takes 8 seconds to load, shows you 4 interstitial ads, and gives you an answer you're not sure is correct. We wanted to build fast, clean utility sites at scale. One at a time was too slow. The question: could AI agents do the heavy lifting? The Architecture: Karpathy's Autoresearch, Applied We took Andrej Karpathy's autoresearch pattern — AI systems that propose, execute, measure, and iterate