9 Most Popular Startups on YC Demo Day

Y Combinator’s summer 2025 demo day attracted more than 160 startups, with a significant shift in its business from AI products to AI agent infrastructure and profitable tools. Popular companies include Autumn (a Stripe-like billing system for AI startups), Dedalus Labs (a Vercel service for AI agents), and RealRoots (a $782,000 monthly revenue for AI friend matching). Other highlights include Solva (AI Insurance Claims Automation, $245,000 in annual revenue), Perseus Defense (low-cost anti-UAV missiles for military purposes) and Pingo AI (AI Language Tutor with $250,000 in monthly revenue). Investors have shown strong interest in professional AI infrastructure and rapid revenue growth.