AfterQuery, founded in January 2025 by Spencer Mateega, Carlos Georgescu, and Danny Tang and launched through Y Combinator's Winter 2025 batch, captures how real-world experts reason and converts it into high-quality AI training data. The company builds datasets, benchmarks, and reinforcement-learning environments sourced from a network of more than 100,000 verified professionals across domains such as finance, medicine, and law, addressing the growing scarcity of expert reasoning data for advanced LLMs and agents. AfterQuery says every major AI lab now uses its services and that it reached roughly $100M in annualized revenue within about 14 months of founding. In April 2026 it raised a $30M Series A at a $300M valuation led by Altos Ventures, joined by The Raine Group, Y Combinator, BoxGroup, and angels from Anthropic, OpenAI, DeepMind, Meta, and Microsoft, to expand its expert network and enterprise offerings.