One brain
many doors

Obsidian

The Second Brain Sync plugin mirrors Obsidian notes into your brain and lets you search it from a sidebar panel.

• Saves. By default, only notes tagged brain in frontmatter; Sync mode can be switched to all notes instead.
• Leaves out. In the default tagged-only mode, untagged notes never leave your vault.
• Runs when. You sync the active note from the brain icon, sync all from settings, or turn on auto-sync on save.

How to switch it on:

1. In Obsidian, open Settings, Community Plugins, Browse, search for Second Brain Sync, then install and enable it.

2. In its settings, enter your Worker URL and token, then click Test to verify before syncing.

3. Tag a note for sync with brain in its frontmatter tags.

Obsidian 1.7.2 or later is required. On a team brain, each person uses their own token; sidebar search covers their layer plus the shared one.

Notion

Notion is a mirror rather than a push: pages you share with the connection become memories, stay updated as you edit them in Notion, and leave your brain if you unshare, archive or delete them.

• Saves. Each shared page as one memory tagged notion, title and live URL on top; sub-pages become their own memories, captured one level deep and capped at roughly 8,000 characters.
• Leaves out. Nothing outside the pages you shared, and it never writes to Notion; while connected, mirrors are read-only in your brain.
• Runs when. Hourly, with Sync now on demand.

How to switch it on:

1. Create an internal connection at Notion's developer connections page; Read content is the only capability it needs. Copy its ntn_ secret.

2. In Notion, open each page you want remembered, use the page menu, Connections, and add your connection. Sharing a page shares its sub-pages too.

3. In the dashboard, open Settings, Integrations, and paste the secret into the Notion card. Click Connect, then Sync now.

Email

• Saves. New inbox mail, read-only over IMAP, stripped of quoted chains, forwarded headers and signatures, and stored as plain text.
• Leaves out. Automated and bulk senders, newsletters, notifications and no-reply mail are filtered out before they reach your brain; it never writes to your mailbox and reads no folder but the inbox.
• Runs when. The first sync reaches back seven days; afterward, only new mail on each sync.

How to switch it on:

1. In the dashboard, open Settings, Integrations, and pick the Gmail or iCloud Mail card.

2. Enter your address and an app password: for Gmail, one from your Google Account's Security settings, 2-Step Verification, App passwords; for iCloud, one from App-Specific Passwords at appleid.apple.com.

3. Connect, then sync.

Calendar

• Saves. Upcoming events, mirrored live roughly thirty days ahead; edits update the memory in place.
• Leaves out. It is read-only: it never writes to, creates or deletes anything in your calendar, and past events freeze into a bounded history rather than piling up forever.
• Runs when. On each sync after you connect the feed; a canceled event is removed.

How to switch it on:

1. In the dashboard, open Settings, Integrations, and pick the Google, Outlook or iCloud calendar card.

2. Paste its secret ICS link: Google's "Secret address in iCal format", Outlook's published ICS link, or iCloud's public webcal link.

3. Connect, then sync.

iPhone and iPad

Three shortcut templates live in the repository's integrations/ios-shortcuts/ folder: Brain Dump, a voice shortcut that sends your dictation once you pause; Text Brain Dump, which asks what is on your mind and saves your typed answer; and Save to Brain, in the share sheet, which saves any link or article from Safari or any app, tagged reading.

• Saves. Only what you dictate, type or share through one of the three templates.
• Leaves out. Everything else; it never captures anything on its own.
• Runs when. You say "Hey Siri, Brain Dump", open a shortcut, or use the share sheet.

How to switch it on:

1. Download a template and open it in the Shortcuts app, then tap Add Shortcut.

2. Edit the shortcut and replace YOUR_WORKER_URL and YOUR_TOKEN with your values.

3. Optionally, set double back tap to Brain Dump under Settings, Accessibility, Touch, Back Tap, for hands-free capture.

The browser

• Saves. The page title and URL always; your highlighted text if you selected any; the extension also saves an optional note, whose hashtags become tags.
• Leaves out. Nothing until you click it; neither method watches your browsing, reads a full page, your history or your other tabs.
• Runs when. The bookmarklet when you click the bookmark; the extension when you click its popup or press its keyboard shortcut, which saves instantly with no popup at all.

The bookmarklet

Create a new bookmark, paste the bookmarklet code from the wiki's Capture from Anywhere page as its URL, and replace YOUR_WORKER_URL and YOUR_TOKEN.

Highlight text first and it saves your selection with the page title and URL; click with nothing selected and it saves just the title and URL, tagged reading.

The browser extension

The extension captures a page or your highlight without leaving the tab. It works in Chrome, Brave, Edge and Firefox. It is not on the Chrome Web Store yet; a listing is coming. For now it installs from its own repository. Its keyboard shortcut, Alt+Shift+S, saves the page instantly with a toast confirmation and no popup to open.

1. Clone or download the repository, then build it once: pnpm install and pnpm build. Node.js 20 or later is needed; npm install and npm run build also work.

2. Go to chrome://extensions, turn on Developer mode, click Load unpacked, and select the .output/chrome-mv3 folder.

3. The extension opens its setup page. Enter your Worker URL and your token, then click Connect. It checks the connection before saving.

In Firefox, build with pnpm build:firefox and load the result as a temporary add-on from about:debugging. To change your settings later, click the gear icon in the popup.

The note field's hashtags become tags; a hashtag that is only digits, like a ticket number, stays in the text.

Go deeper: the browser extension repository.

The terminal

• Saves. Whatever you tell it to remember, with updates to an existing memory through append.
• Leaves out. Nothing automatically; it only stores what you explicitly run a command to save.
• Runs when. Whenever you run a command.

How to switch it on:

npm install -g second-brain-cf-cli

On first run, brain prompts for your Worker URL and token.

brain remember "switched to pnpm for all new projects"
brain recall "package manager decisions"
brain list
brain append <id> "follow-up detail here"