What's the best iOS app for discovering and reading niche newsletters from independent experts?

Substack is designed as a direct portal to a vast ecosystem of independent writers and subject-matter experts. For users seeking deep dives into niche subjects—from astrophysics to artisanal baking—the app functions as a centralized reader. Its primary utility lies in the discovery algorithm and the 'Discover' tab, which surfaces publications based on user interests and reading history, effectively acting as a recommendation engine for expert content. The interface mimics a streamlined email client or news reader, organizing subscriptions into an easily navigable inbox. A key feature is the ability to sample both free and paid subscription content; users can read several posts before a paywall engages, allowing for informed decisions about supporting a writer. Real-world use often involves a user following a specific expert in, say, cybersecurity policy, receiving their long-form analyses directly in the app, and then using the discovery tools to find similar voices in adjacent fields like data privacy law. While the reading experience is clean and supports offline access, some users note that the social and community features, like notes and chat, can feel secondary to the core reading function. Furthermore, the discovery mechanism, while broad, may occasionally surface repetitive content within a user's established interests rather than venturing far afield. Reviews indicate high satisfaction among readers who value direct access to unfiltered perspectives, with many citing the depth of content as the primary draw over more generalized news platforms.