Share your Kindle library privately and let friends vote on what you read next (social voting + privacy)

Many avid readers—estimated as part of the 200 million active digital readers—struggle with what to read next and with sharing reading choices without exposing purchase history or private highlights; informal groups on Discord, Instagram and among friend circles currently resolve this with ad hoc polls or public Goodreads lists that leak data and require manual effort. This creates a clear pain point for privacy-conscious, socially engaged readers who want low-friction collaborative decision-making without publicizing their entire library. You could build a privacy-first social voting product that syncs with Kindle and Readwise exports, lets users share an anonymized, permissioned subset of their library with invited friends, and runs lightweight vote mechanics (ranked choice, shortlists) augmented by AI-generated summaries and blurbs to speed decisions. Monetization would combine a $30/year subscription tier for advanced group features and syncing, plus a marketplace fee on book-related services; with a target ARPU of $30 the TAM approximates $6.0B and supports modest scale economics if engagement and retention are strong. The timing is favorable because cross-platform export tools and growing social-reading behaviors reduce technical friction and raise demand, and AI can shrink a typical discovery workflow from hours to minutes. Differentiation will hinge on trustable privacy defaults, seamless Kindle integration, and a product optimized for small conscious groups rather than mass public feeds; the main challenges are dependency on Amazon/third-party integrations, initial user acquisition, and converting engaged groups into paid subscribers despite a medium-competition landscape and a revenue potential rated 72/100.