Privacy policy

secondbrain. Effective 5 September 2026.

secondbrain is a private notebook. It keeps what you put into it, for you, and does nothing else with it. This page says exactly what that means, in the order you would want to ask.

What we store

Only what you put in, plus the little it takes to let you back in:

• Your tasks, notes, pages, shopping list, and the finance figures you mirror across from your own computer.
• Meeting transcripts, when you choose to record a meeting. Nothing is recorded unless you start it.
• Your email address, which is your account.
• A name for each signed in device, so you can tell your phone from your laptop and sign one of them out.

There is no profile, no advertising identifier, and no history of what you tapped.

Where it lives

On Cloudflare's network. Your account gets its own private database that holds nothing but your own things, separate from every other account. A short separate list holds accounts themselves: the email address, the signed in devices, and the sign in codes that have not expired yet. Sign in tokens are stored only as a one way hash, so the stored form cannot be used to sign in as you.

How the AI works

When you ask a question, or let the app sort something you captured, the text of that one request is sent to Anthropic's API and the answer comes back. That is the whole of it. Anthropic does not use what is sent through the API to train models, and neither do we. Nothing is sent unless a feature you used needs it, and the rest of your notebook stays where it is.

What we never do

• No advertising, and no advertisers.
• No tracking, no analytics SDK, no third party scripts. This page itself loads nothing from anywhere.
• No selling, renting, or sharing your data with anyone. There is nobody to sell it to and no plan to find one.

Your controls

• Export. Take everything, any time, as one file you keep.
• Delete. Delete your account from the app. Your database is wiped in the same moment.
• Devices. See every device signed in to your account and revoke any of them, including one you have lost.

How long we keep it

Your things stay until you delete them. A deleted account is wiped immediately, not queued for later, and it does not come back. Sign in codes expire ten minutes after they are sent. A device that stops being used lapses on its own after a year, and has to sign in again.

Changes to this page

If this changes in a way that matters, the date at the top changes with it and you will be told in the app before it takes effect.

Questions

Write to [support address]. A real person reads it.