Karakeep is a self-hostable bookmarking and read-it-later application. It supports saving links, notes, images, PDFs, and videos, with AI-powered auto-tagging, summarization, and semantic search. The system consists of a Next.js web app, an Expo React Native mobile app, a browser extension (Chrome/Firefox/Safari), a CLI, a Model Context Protocol (MCP) server, and a set of background workers (crawler, embeddings, feeds, webhooks, rule engine, backups). The backend uses tRPC for API, Drizzle ORM with SQLite, and a plugin system for swapping infrastructure (asset stores, queues, search, rate limiting). The architecture is monorepo with shared packages for types, server utilities, and React hooks. It is actively maintained with frequent releases and a large community.