InboxCross

InboxCross is a web app + browser extension that helps Substack and newsletter writers systematically convert email subscribers into followers on other platforms where monetization is stronger (YouTube, Patreon, courses, communities). Today, most writers have a decent email list but a weak cross-platform presence because manually tracking who clicks what, who buys, and who engages on social is tedious and fragmented. InboxCross plugs into Substack, ConvertKit, Beehiiv, and social APIs to build a unified engagement graph for each subscriber. It then recommends and automates targeted CTAs: who should be pushed to a paid tier, who should be nudged into a course, who should be invited to a Discord/Slack, and who is likely to churn. Instead of generic “follow me on X” links, it generates smart, segmented callouts and link blocks that adapt to each reader’s past behavior. The brutal reality is that most newsletter writers will never make real money from subscriptions alone; InboxCross is built to squeeze more revenue out of the same list by intelligently routing readers to higher-value funnels with minimal manual work.