Daily Kos isn’t just a media publisher, it’s a 20-year-old community where readers write, organize, and show up every single day. When it was time to migrate 1.5 million posts, 2.7 million users, and 88 million comments off a custom-built CMS, the technical challenge was only half the problem. The real risk was losing the trust of the people who fund 90% of the platform. In this session, the CTO of Daily Kos, and the staff engineer walk through what it took to migrate a community-first platform: The scale: 1.5M posts, 2.7M users, 88M comments, and two decades of technical debt The decisions that mattered: architecture choices made around user psychology, not just infrastructure What we learned and what we’d do differently How we ran a fully public beta with 500+ vocal community members, and what we learned