Most note apps keep your notes on someone else's server, in a format only that app can open. Obsidian does the opposite. Your notes are ordinary Markdown text files in a folder on your computer, which Obsidian calls a vault. If the app disappears tomorrow, your notes are still readable in any text editor.
What Obsidian actually is
It is a note-taking and knowledge app built around links. You write in Markdown, and you connect notes by typing a note's name in double square brackets. Obsidian then shows each note's backlinks, meaning every other note that points to it, and a graph view that draws your notes as a connected map.
The app itself is small. Most of its power comes from plugins: built-in ones such as Canvas, a whiteboard-style space for arranging notes, and a large community plugin library for things like calendars, task lists, and templates.
What it costs
These are the prices on Obsidian's own pricing page as of October 2026:
There is also an optional commercial license at $50 per user per year. It supports development, but the pricing page says it is not required. Students, faculty and nonprofit employees get 40% off Sync and Publish.
The cost-benefit, honestly
If you only need notes on one device, Obsidian costs nothing, and that is hard to beat. The real decision is syncing. At $4 a month billed annually, Sync is $48 a year. The free alternative is to put your vault in a cloud-storage folder you already pay for, such as iCloud or Dropbox. That works for many people, but you manage conflicts and phone setup yourself. So Sync is paying for convenience and encryption, not for a feature you cannot get otherwise.
Publish is $96 a year for one site. Compare that with free static hosting if you are comfortable with a little setup. It makes sense mainly if you want a published notebook with no setup at all.
Who it is great for
People who want to own their notes for the long term, writers and researchers who think in connections, anyone who already likes Markdown, and anyone who wants to feed their own notes to AI tools, since plain files are easy to read programmatically.
Who should skip it
Teams that need real-time editing together may find it awkward: the strength is a personal vault, and shared vaults are a paid add-on. If you want a polished all-in-one workspace with databases and a web app out of the box, a hosted tool will feel easier. And there is a learning curve: a blank vault with no plugins can feel bare, and some people spend more time tuning plugins than writing.
One more thing to know: Obsidian is free to use, but the app itself is not open source, even though your notes are in open formats.
How to start in 10 minutes
Download the app from obsidian.md, create a vault in a folder you already back up, and write one note a day for a week. Link notes only when the link is obvious. Add plugins one at a time, only when you hit a real problem. Skip Sync until you actually need your notes on a second device.