Obsidian

Obsidian is a local-first markdown note-taking app designed for building interconnected knowledge bases. It supports bidirectional links, graph visualization of note relationships, backlinks, and custom community plugins for extended functionality. With no vendor lock-in (files stored locally), it’s ideal for researchers, writers, and knowledge workers. Core features are free, while paid add-ons like Sync (for cross-device sync) and Publish (for web sharing) enhance collaboration and accessibility.