Last updated: October 18, 2026
The short version: your books, your audio, your reading activity, and your AI conversations stay on your Mac. The one exception is cloud processing, which you choose: documents you add on unknown.ac, on an iPhone or iPad without a Mac, or on a Mac that can't convert them itself are converted on our servers and then deleted (section 2). If you use more than one device, your reading progress, document titles, bookmarks, notes and mind maps sync through your account (section 2). We collect the minimum needed to run accounts, subscriptions, and crash reporting - never the contents of what you read. We do not sell data, show ads, or train AI models on anything of yours.
Unknown is built so that the private parts of reading stay on your machine. When the Mac app converts a document itself, which it does whenever it can, nothing below ever leaves your Mac. Cloud processing, described in section 2, is the only path that sends a document to us, and only when you use it.
A few narrow things do involve a network, and we list all of them here.
If you sign in (Sign in with Apple or Google), we receive your name and email address through Firebase Authentication. This exists so your subscription can be restored across devices. We use it for nothing else - no marketing emails, no profiling.
Subscriptions bought in the iPhone or iPad app are processed by Apple through the App Store; subscriptions bought on the Mac or the web are processed by Stripe. RevenueCat keeps your subscription status in sync across them. They handle payment details; we never see or store your card number. We receive your subscription status and purchase history linked to a pseudonymous identifier.
Some documents are converted on our servers instead of on your Mac: documents you add in the web reader at unknown.ac/listen, documents you add on an iPhone or iPad when you have no Mac, and, with your permission, documents on a Mac that can't run the converter (for example an Intel Mac). In those cases the document, or the link you pasted, is sent over TLS to our processing service, which runs on Modal's GPU servers. It is converted by the same software the Mac app uses, and the result (the document, its audio and the extracted text) is kept only so your devices can download it: 7 days, or 90 days for documents added on the web so they can reach the apps you sign in to later. Removing a document from the web reader deletes it right away. Files are tied to your account ID, are never read by a person, and are never used to train AI models. The web reader also keeps a copy of your converted documents in your browser's storage, which signing out clears. When you paste a link to a public web page or paper, the converted result may be cached for up to 90 days and reused when anyone converts the same link in the same voice; documents you upload are never shared this way.
If you sign in on more than one device, Unknown keeps your library in sync. Small library state (reading position, document titles, collection names, bookmarks, notes and mind maps) is stored in Google Firebase (Cloud Firestore) under your account ID. Document files and audio sync through your own iCloud Drive or download from cloud processing; they are not stored in Firebase. This data is used only to sync your devices and is deleted when you delete your account.
If the app crashes, a crash report (stack trace, app version, macOS or iOS version, device model) is sent to Sentry so we can fix it. If you file a bug report from inside the app, the app log you choose to attach is included; logs are designed to describe what the app did, not what your documents say.
We record which features are used (for example, that a narration was started or a mind map was created) via PostHog, with app version and device model. These events never include document contents, document names, page text, voice audio, or chat messages.
The app periodically checks unknown.ac for updates (via Sparkle). This is a standard web request and involves no account or personal data beyond your IP address, which is not logged by us.
Connecting a calendar is optional. If you connect Google Calendar so Unknown can schedule listening sessions around your meetings:
Calendars connected through macOS (Apple Calendar via EventKit) are read with the system permission you grant and are handled entirely on-device.
unknown.ac uses Google Analytics, PostHog and Ahrefs Analytics to measure aggregate traffic (pages viewed, approximate region, download clicks, and which web addresses are opened through unknown.ac/open). With your consent where the law requires it, the site also uses the Meta and X advertising pixels so we can show Unknown ads to people who have visited. Visitors in Europe are asked first, and anyone can change their choice in Cookie settings. No account is needed to browse or download, and website data is never linked to your in-app identity.
Local data (books, audio, chats, reading progress) lives on your devices and is yours to delete; uninstalling the app removes it. Crash reports and analytics events are kept only as long as needed to maintain the app. You can delete your account from inside the app (on iPhone and iPad: library, gear icon, Delete Account). That removes your sign-in, your synced library data and any documents still on our processing service right away. You can also email support@unknown.ac and we will complete the deletion within 30 days. An App Store subscription is billed by Apple and must be cancelled in your App Store account settings.
The few network calls the app makes use TLS. Calendar tokens live in the macOS Keychain. Locked books require Touch ID. Documents processed on-device never exist on a server. Cloud-processed documents are stored on our processing service only until the retention period in section 2 ends.
Unknown is not directed at children under 13, and we do not knowingly collect personal information from them.
If this policy changes, the latest version will always be at this page with an updated date. We will not weaken the commitments in section 1 and section 5 without asking for your consent in the app.
Questions or requests? Reach us at support@unknown.ac.
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