Readwise is a reading and knowledge management tool that helps avid readers, knowledge workers, researchers, and writers retain and use what they read by resurfacing highlights from Kindle, Instapaper, Pocket, and PDFs through daily review emails and spaced repetition. Readwise connects a fragmented reading workflow into a single knowledge base, and the native sync with Obsidian and Notion means highlights flow automatically into users' existing second brain or note-taking setup. Readwise Reader adds a built-in RSS reader and read-later app so users can capture, read, and highlight articles and newsletters without switching between services. For anyone serious about building a personal knowledge management system from their reading, Readwise is the connective layer that makes highlights actionable over the long term.