Sim (@simdotai) is building the visual, end-to-end agent builder — a platform where developers can design, test, and deploy real AI agents that work in production. Founded earlier this year, Sim grew from a small San Francisco apartment to a community of 60,000 developers and 18,000 GitHub stars, recently raising a $7M Series A. Co-founder & CEO @emkara sat down with YC’s @aaron_epstein to share how they’re building the infrastructure for the agent era, and what it takes to create AI systems that reason, retrieve, and act safely at scale. 00:36 – What Sim Does and Why It Matters 02:05 – From a SF Apartment to 60,000 Devs 04:20 – Finding Early Users and Product-Market Fit 07:05 – Designing an End-to-End Platform for Agents 10:30 – Powering the Open Source Agent Ecosystem 13:25 – Raising a $7M Series A 16:20 – Building Agents That Actually Work 20:10 – The Infrastructure for the Agent Era 23:40 – Advice for Builders in AI