Obsidian is a note-taking application that stores all notes as plain Markdown files on your local machine. The core concept is bidirectional linking you can link between notes using double brackets, and Obsidian tracks all connections, displaying them as a visual graph.
The local-first approach is a deliberate design choice. Your notes are plain text files that you own completely they can be opened in any text editor, backed up with any tool, and will remain readable regardless of whether Obsidian continues to exist as a product.
For developers and technical writers, Obsidian is well-suited for building a personal knowledge base. The Markdown format means code blocks, technical content, and structured writing all work naturally. The plugin ecosystem includes tools for tasks, spaced repetition, and integration with external services.
For researchers and students, the linking system helps build a network of connected ideas over time. Unlike a folder-based system where notes are isolated, Obsidian's graph reveals unexpected connections between topics you have written about at different times.
Free for personal use with local storage. Obsidian Sync at 8 dollars per month for encrypted cross-device sync. Obsidian Publish at 8 dollars per month for publishing notes as a website.