Short answer
For a second brain only you read, pick Obsidian: it is free and every note is a markdown file an AI can open. Pick Notion when the brain is mostly databases shared with others. If a team and an AI both need it, neither fits cleanly: Obsidian shares whole vaults only, and Notion's MCP reaches every page you can open.
For a second brain that only you read, Obsidian is the better pick: it is free, and every note is a plain markdown file in a folder on your own disk. Notion is the better pick when the second brain is really a set of databases you share with other people. The feature tables miss the part that decides it, which is who else has to read the notes.
Every page that ranks for this question compares the two on features: graph view against databases, markdown against blocks, offline against cloud. Those differences are real, and they mostly fall out of one decision each app made early. Obsidian keeps your notes as files. Notion keeps them as rows in its own service. That one choice settles what an AI assistant such as Claude can read, what a teammate can edit, and what you can take with you if you leave.
There are three readers to plan for: you, an AI, and the people you work with. Obsidian is built for the first and handles the second well. Notion is built for the third. If the second brain needs all three, neither covers it cleanly, and that is the gap Baalda was built for: the same markdown files Obsidian gives you, with live editing, per-folder permissions and an AI connection on top. The rest of this post covers each reader in turn, and where each tool is the wrong answer.
What is the actual difference between Obsidian and Notion?
Obsidian's own docs put it in one sentence: "Obsidian stores your notes as Markdown-formatted plain text files in a vault. A vault is a folder on your local file system". The app is a reader and editor for that folder. Close Obsidian and the notes are still there, readable in any text editor.
Notion is a cloud workspace. A note is a page made of blocks, and a page can be a row in a database with properties, relations and views. That is what makes Notion good at the structured half of a second brain, such as project lists, reading queues and anything you want to sort and filter. It also has linked thinking: backlinks are created automatically every time you @-mention a page, so the claim you will see on some comparison pages that Notion cannot connect notes is out of date.
| Obsidian | Notion | |
|---|---|---|
| Where a note lives | a markdown file in a folder on your disk | a page in Notion's cloud workspace |
| Structure | folders, links, tags, properties | pages, databases, relations, views |
| Price for one person | free, a commercial licence is optional | Free plan, Plus at $10 per member per month |
| Sharing | whole vault through paid Sync | per page, built in |
| AI access | anything that can read a folder | Notion MCP, with your full permissions |
| Leaving | the files are already yours | export to markdown, databases become CSV |
The prices are from Obsidian's pricing page and Notion's pricing page, as of 19 October 2026.
Which is better for a second brain with Claude or another AI?
Obsidian, for one person, and by a wide margin. An agent that works on files, such as Claude Code started inside the vault folder, reads and edits the notes directly with no connector at all. Obsidian also added an official command line tool in version 1.12 in February 2026, which lets you control Obsidian from your terminal, though it needs the Obsidian app running. For a chat app such as Claude Desktop, you add an MCP server that points at the folder, and the ones in common use for Obsidian are community projects, compared in MCP servers for Obsidian.
Notion's route is its own MCP server, which lets assistants like Claude, ChatGPT and Cursor read from and write to your Notion pages. It works well. The catch is scope, and the same help page states it: MCP tools act with your full Notion permissions and can access everything you can access. In a personal workspace that is fine. In a shared workspace, the assistant reaches every page you can open, not just your second brain, which is the subject of connecting Claude to Notion.
Notion's own AI is the other route, and the full version sits on the Business plan at $20 per member per month. On the Free and Plus plans it is listed as a trial.
What happens when a second person needs the second brain?
This is where the two swap places.
Notion was built for it. You share a page, set what each person can do, and you are editing the same page at the same time. If your second brain is going to become the team's, Notion gets there with no extra setup.
Obsidian gets there through Sync, and the limits are in its own help page on shared vaults:
- "All collaborators must have an active Sync subscription to access a shared vault", at $4 per user per month billed annually.
- "All collaborators receive the same permissions as the vault owner." There is no per-folder or per-file control.
- "Obsidian does not yet support collaborative live editing on the same file." Edits made at the same time are merged when the devices sync.
- A shared vault takes at most 20 collaborators.
So the person who chose Obsidian for the files ends up with a team setup where everyone pays, everyone can change everything, and two people in the same note find out on sync. The longer version, with the other ways to share a vault, is in how to share an Obsidian vault.
Where does Baalda sit between Obsidian and Notion?
Baalda keeps Obsidian's storage model and adds what Notion has for a team. Notes are plain markdown files in a folder on your disk, so an agent working on files reads them the way it reads an Obsidian vault. On top of the files:
- Live editing. Several people edit one note at the same time over CRDTs, which merge each change as it is typed rather than at the next sync.
- Permissions per folder and per file. A folder can be
editfor one person,viewfor another andnonefor everyone else, and a grant on a folder applies to everything inside it. - An AI connection scoped to one vault. Baalda serves MCP at
https://api.baalda.com/api/mcp(or your own server's URL with the same path). A token is scoped to you in one vault and goes through the same per-folder permissions as you do, so the assistant reaches that vault, not every page you have ever been shared.
claude mcp add --transport http context https://api.baalda.com/api/mcp \
--header "Authorization: Bearer mcp_…"It is open source under Apache-2.0 and can be self-hosted. Locally it is free, the managed service is free for 2 people and 1 synced vault, and the Team plan is $10 per seat per month with a minimum of 3 seats.
Which should you pick?
| Your second brain is | Pick |
|---|---|
| yours alone, mostly notes and links | Obsidian |
| yours alone, mostly projects, lists and views | Notion |
| read by Claude or another agent, one person | Obsidian |
| shared with a team, structured as databases | Notion |
| shared with a team, and an AI reads and writes it | Baalda |
If you are unsure, start with the shape of what you write. Long notes that link to each other suit files. Rows you sort, filter and assign suit a database. Most people's second brain is the first kind with a small amount of the second, which is why a single project database in Notion, or a few properties in Obsidian, usually covers the structured part. The how-to for each is in a second brain in Obsidian and a second brain in Notion.
Leaving is also easier in one direction. Notion exports any ordinary page to markdown, but full page databases export as CSV files, so a second brain built on relations and rollups loses its structure on the way out. Obsidian has nothing to export, because the files were never anywhere else.
Where is Baalda the wrong answer?
When the second brain is databases. Baalda has no databases, relations or table views, so a brain built around a project tracker belongs in Notion.
When you need it on your phone. Baalda runs on macOS, Windows and Linux, with no mobile app yet. Obsidian and Notion both have one.
When you live in plugins. Obsidian's community plugins have no equivalent in Baalda, and neither does Obsidian Publish.
And when it is only you. A second brain with one reader does not need live editing or permissions, and Obsidian already does that job well and for free. The full comparison is on Baalda vs Obsidian and Baalda vs Notion.