ListSplit

ListSplit is a web app + browser extension that lets Substack and newsletter creators automatically segment, clone, and reposition their existing publication into multiple niche, higher-CPM spinoff newsletters. Instead of endlessly trying to grow one bloated list, creators can use ListSplit to analyze their archive, identify distinct content themes and reader behaviors, and spin those into separate, tightly focused newsletters with their own landing pages, onboarding flows, and sponsor positioning. The app ingests your Substack (or other newsletter platform) via API, clusters posts and engagement metrics, and suggests 2–5 viable sub-niches with concrete content angles, audience personas, and monetization strategies. It then generates draft landing pages, welcome sequences, and sponsor one-pagers tailored to each sub-niche. This is not about vanity growth; it’s about carving out smaller but more valuable lists that advertisers will actually pay for. It’s a brutally pragmatic tool for creators who are stuck at a plateau, sitting on years of content and data, but don’t have the time or strategic clarity to restructure their audience into something that makes real money.