How My Company Built an AI App So Good We Sold It for $650 Million

In this Y Combinator Startup School talk, Jake Heller, co-founder and CEO of Casetext, explains how his team stopped everything at $20M in revenue to build CoCounsel, the first AI assistant for lawyers, on early access to GPT-4 — a bet that led to a $650 million acquisition by Thomson Reuters. He lays out a practical playbook across three areas: how to pick an idea (target jobs people already pay for, in categories of assist, replace, or do the previously unthinkable), how to actually build reliable AI (map exactly what a professional does, turn each step into prompts or plain code, and grind on evaluations until you pass 97-99% of tests), and how to market and sell it (build a genuinely great product first, price to value, build trust with head-to-head comparisons, and watch out for pilots that never convert to real revenue).