President & CEO of Y Combinator since January 2023. Co-founded Posterous (YC W08, acquired by Twitter) and blog platform-era design tooling before becoming a YC partner (2011-2015). Co-founded Initialized Capital with Alexis Ohanian, backing Coinbase at seed — one of the best seed checks in venture history — plus Instacart and Flexport. Known for founder-first, design-literate early-stage investing and a large builder audience on YouTube.