Obsidian

Obsidian is a free note-taking app that turns a plain folder of Markdown files into a personal knowledge base. Your notes live on your own device, open quickly even offline, and stay readable in any text editor, so what you write today remains yours for the long term. It fits journaling, research, study notes, writing projects and anyone building a second brain.

Build a Web of Linked Notes

Links are at the heart of Obsidian. Connect any note to any other with a quick link, and the app tracks the relationship in both directions, so you can see which ideas point back to the one you are reading. Over time a pile of meeting notes, book highlights and stray thoughts becomes a personal Wikipedia you can wander through, from people and places to projects and half-formed ideas.

See Your Thinking Take Shape

The graph view draws your notes and their connections as an interactive map, revealing clusters and hidden patterns in your thinking. Canvas gives you an infinite space to research, brainstorm, diagram and lay out ideas side by side: drop in notes, images and links, then move them around until the shape of a project becomes clear.

Make It Work Your Way

Thousands of community plugins and themes let you shape Obsidian around your habits. Add a calendar with daily notes for journaling, kanban boards for projects, spaced repetition for studying, or task management for your to-do lists. You can start with the plain editor and adopt new pieces only when a real need appears.

Your Notes Stay Yours

Everything is stored locally in open file formats, with no account required and no telemetry collected, so you are never locked in. If you stop using Obsidian tomorrow, every note is still an ordinary file you can open elsewhere, and you can use the app without sharing any personal information at all.

Free, With Optional Paid Services

The app itself is free without limits and needs no sign-up, with apps for Windows, macOS, Linux, iOS and Android. It is proprietary software rather than open source, but development is user-supported: optional paid services add end-to-end encrypted synchronization across devices (Sync) and publishing notes to the web as a fast site (Publish), while Catalyst and Commercial licenses exist for those who want to fund the project.

Things to Know Before You Rely on It

Syncing notes between devices is not included for free: you either subscribe to Sync or arrange your own method with third-party tools. Community plugins are third-party code, so stick to popular, actively maintained ones. And because everything is plain local files, real-time collaboration is more limited than in cloud-first tools such as Notion.

Editorial note: the first screenshot, "Screenshot of Obsidian Callouts" by DoULikeIce (CC BY-SA 4.0, via Wikimedia Commons), shows the Obsidian note renderer displaying callouts. The second image is an official example of the Obsidian Publish service, not the desktop app.