How your journal is protected
Written plainly, including the parts that aren’t perfect. Last updated September 30, 2026.
- Your journal lives on your device. It works with no connection and no account.
- If you turn on sync, entries are locked on your device before they leave it. Our servers only ever hold scrambled text. We can’t read your journal, even if we wanted to.
- Your password never leaves your device. Sign-in only receives a one-way fingerprint of it, which can’t unlock your entries.
- Claude only sees what you send when you press a Claude button. Nothing is sent in the background.
- No ads. We never sell your data. Your journal is never used to train AI.
- Export everything or delete your account any time.
Where your journal lives
Everything you write is saved in your browser’s storage on your phone or computer, and Brainlore works fully offline. Without an account, your entries never leave that device. The trade-off: if you clear your browser data or lose the device, those entries are gone, so export a copy now and then (More → Your words are yours).
If you turn on sync
With an account, your entries follow you to your other devices. Before any entry leaves your device, it is encrypted there:
- Your device turns your password into a key (PBKDF2-SHA-256, 310,000 rounds) and locks each entry with it (AES-256-GCM, a standard used for banking and messaging).
- The key is created and kept on your device and can’t be exported from it. It is never sent to us.
- To sign in, your device sends a separate one-way fingerprint of your password, made differently from the key. Our sign-in provider stores only a hash of that fingerprint. Neither can be turned back into your password or your key.
- Our database stores the locked entries plus the few facts sync needs: an entry ID, when it was last changed, and whether it was deleted.
If you forget your password, nobody can unlock the synced copies, including us. That’s the price of real privacy. You can reset your password from a device that still has your entries: that device re-locks them with the new password and uploads them again.
When you use a Claude feature
Claude (made by Anthropic) powers the AI features. Nothing goes to Claude unless you press a Claude button, and then only what that feature needs:
| Feature | What’s sent |
|---|---|
| Give me three sparks | Your mood check-in, and short excerpts of your last three entries if that box is ticked |
| Talk it out | The conversation so far, the time of day, short excerpts of recent entries if that box is ticked, and the text of your last few small steps with how they went (so a new step is the right size). The app asks the first question itself, so nothing is sent until you answer. |
| I’m stuck | The draft you’re writing |
| Reflect | That one entry |
| Ask about your journal | Your question, and short excerpts of the entries it finds. The searching itself happens on your device. |
| Receipts | Your entries from that week, including any small step you chose in them. The week’s totals are counted on your device and aren’t sent. |
| Offline pack | Short excerpts of recent entries |
This part is not end-to-end encrypted: to answer, Claude has to read the text. It travels encrypted over the internet (HTTPS) through our server to Anthropic. Our server passes it along and doesn’t store it. Anthropic does not train its models on it and deletes it within 30 days, except requests flagged for violating its usage policy, which it may keep for up to 2 years. Claude’s replies are AI-generated and can be wrong. They are not therapy or medical advice.
Everything we store on our servers
| What | Why | Readable by us? |
|---|---|---|
| Your synced entries | Sync between your devices | No, locked with your key |
| Your email and sign-in fingerprint hash | Signing in, password reset | Email yes; the fingerprint only as a hash |
| Your access code and daily usage counts (number of Claude uses and tokens per feature) | Fair-use limits and knowing what the AI costs | Yes, counts only, never content |
| Feedback you send | Improving Brainlore | Yes. It includes which screen you were on, whether the app is installed, and your browser type. Never journal content. |
| Reminder settings, if you turn reminders on | Sending your daily reminder | Yes: a notification address for your device, your time, time zone and language |
| Your email, if you join the founding-member list | Emailing you once when paid plans open | Yes. Only your email, language and where you heard about us. |
| Anonymous usage events (you can turn these off) | Seeing which parts of Brainlore help people keep going | Yes: a random ID made on your device (not your account or email), the event name (like “entry saved”), language and time |
Music
If you add a YouTube or Spotify link to your journaling playlist, the link is saved on your device only, and that service’s own player loads inside Brainlore. YouTube (through its privacy-enhanced mode) or Spotify can see that you’re playing it, as they would anywhere else. Nothing from your journal is shared with them.
What we never do
- Sell or rent your data, or share it with advertisers. There are no ads.
- Use your journal to train AI.
- Read your synced journal. We can’t.
- Send your journal anywhere without you pressing a button.
Your controls
- Export: More → Your words are yours → Download.
- Delete your account and all synced copies: More → Your account → Delete my account. It’s immediate.
- Clear this device: sign out and choose “clear this device”, or clear your browser’s data for this site.
- Usage events: turn them off in More → How your journal is protected.
- Reminders: turn off in More → Daily reminder.
Where it’s processed
Our services run in the United States: Vercel (the app and our server), Supabase (sign-in and the encrypted sync database, US East), and Anthropic (Claude). If you use Brainlore from another country, including Korea, the information in the table above is transferred to the United States for the purposes listed, and kept until you delete it, delete your account, or turn the feature off.
Children
Brainlore isn’t intended for anyone under 14.
If you’re struggling
Brainlore is a journal, not therapy or medical care. If you’re thinking about hurting yourself, please reach out to someone you trust or a crisis line: 988 in the US (call or text), 109 in Korea, or your local emergency number.
Questions
Use Send feedback in the app (More → Send feedback). We’ll update this page when anything changes and note the date at the top.
An independent security review is planned. Until then, everything above describes how the app is built today.