Privacy Policy

Last updated: September 24, 2026

The short version: Marginalia works fully offline by default — your books, highlights, journal, and notes stay in your browser and never touch our servers. If you turn on sync or use the browser extension, you create an account, and from that point on the content you choose to sync is stored on our servers so your other devices can see it. We don't sell your data, we don't run ads, and we don't use your highlights or journal to train anything.

1. Who this policy covers

Marginalia is currently built and operated by an individual developer, not a registered company. For anything in this policy, "we," "us," or "Marginalia" means that developer. You can reach us at privacy@[to be finalized — see note below] for any privacy question, data request, or deletion request.

(Placeholder note: this address will be a free forwarding address on Marginalia's own domain, set up via Cloudflare Email Routing once that domain is purchased — no mailbox to pay for, just a forward to a real inbox. Until then, use the contact link on the app's GitHub repository.)

2. If you never sign in

Everything — your books, highlights, insights, journal entries, canvas boards, saved articles, tags, and settings — is stored only in your browser's local storage (IndexedDB). None of it is sent to us. We have no way to see it, back it up, or recover it if you clear your browser's storage. That's the trade-off of fully local software, and it's the default.

We do collect one thing even if you never sign in: anonymous, cookie-free usage analytics via Plausible Analytics — things like "the Discover modal was opened," never the content of what you read, highlight, or write, never your IP address stored against you, never a persistent identifier that follows you across visits.

3. If you sign in (sync or the browser extension)

Signing in creates an account with an email and password (or a Google account, where offered), hosted for us by Supabase. From then on, whatever you choose to sync is stored in our database, tied to your account, and protected by row-level security so that only your own signed-in session can read or write it — not other users, and not us browsing through it casually.

What that can include, depending on what you use:

Your email address and an encrypted password (we never see or store your password in plain text — Supabase's authentication system handles that entirely).
Book metadata, highlights, reading progress, insights and reflections, journal entries, canvas boards, collections, and tags.
Saved articles and bookmarks — including, if you choose "save full text," the extracted readable text of pages you save.
From the browser extension: the URL and title of pages you save, and the text (plus a little surrounding context, used only to re-find it later) of anything you highlight on the web.

We do not collect your general browsing history, only what you explicitly save or highlight. We do not collect payment information — Marginalia has no paid features yet.

4. How saving an article actually works

When you save a page for full-text reading, a small server-side function fetches that URL on your behalf and extracts the readable text (removing ads, navigation, etc.). That function refuses to fetch anything on a private or internal network address, and it doesn't keep a copy of what it fetches beyond returning it to you.

5. Who else sees any of this

Supabase — hosts our database and handles authentication. They can access infrastructure-level data as any hosting provider can; see Supabase's own privacy policy.
Cloudflare — hosts the web app itself and, if you're using the extension's saved-article fetching, proxies those requests. Standard web server logs apply; see Cloudflare's privacy policy.
Plausible Analytics — anonymous, cookie-free product analytics, described above.
Google — only if you choose "Continue with Google": standard OAuth sign-in, governed by Google's own privacy policy.

We never sell your personal data, and we don't share it with data brokers or advertisers. We don't have ads.

6. How long we keep it, and deleting it

Local data stays on your device until you delete it yourself or clear your browser's storage. Synced data stays in our database until you delete it — trashing and then permanently deleting an item in the app or extension removes it from our servers, not just your view of it. To delete your entire account and everything tied to it, contact us at the address above; we're working on an in-app "delete my account" button so this doesn't always require an email.

7. Your rights

Wherever you are, you can ask us to access, correct, export, or delete the personal data we hold about you, by contacting us. Depending on where you live, this may also be a formal legal right:

European Economic Area / UK (GDPR): you have the right to access, rectify, erase, restrict, or port your data, to object to processing, and to lodge a complaint with your local data protection authority.
California (CCPA/CPRA): you have the right to know what personal information we hold, to request deletion, and to opt out of the sale of personal information — we don't sell personal information, so that opt-out is already the default.
Canada (PIPEDA): you have the right to access personal information we hold about you and to request correction of inaccuracies.

8. Children's privacy

Marginalia isn't directed at children, and we don't knowingly collect personal information from anyone under 13 (or the minimum age required in your country). If you believe a child has created an account, contact us and we'll delete it.

9. Security

All traffic to and from Marginalia is encrypted (HTTPS). Passwords are hashed by Supabase's authentication system, never stored or handled by us in plain text. Database access is restricted by row-level security so your data is only ever readable by your own authenticated session. No system is perfectly secure, and we can't guarantee absolute security — but this is what we've built to protect you.

10. International data transfers

If you use sync, your data is processed and stored on infrastructure that may be located outside your own country (Supabase and Cloudflare operate global infrastructure). By using sync, you consent to that transfer.

11. Changes to this policy

If we materially change how we handle your data, we'll update the date at the top of this page and, where practical, let signed-in users know inside the app.

12. Contact

Questions, requests, or concerns about your data: privacy@[to be finalized], or open an issue on Marginalia's GitHub repository.