Lexfolio: privacy notice

Lexfolio has no account system, no sign-in, and no server operated by us. There is no advertising SDK and no analytics collector. We do not receive your name, your email address, your location, your library, or anything you read or write inside the app. The one exception is a record of a purchase, described under Purchases below.

What stays on your device

Everything you bring to Lexfolio and everything you make in it is processed and stored on the device itself:

• the EPUB and PDF files you import
• reading positions, highlights, notes, and pinned margin notes
• vocabulary entries, spaced-repetition cards, concepts, and Knowledge Threads
• passage alignments, research projects, citations, and bibliographies
• offline search indexes and concordances
• text recovered by OCR

Deleting the app removes all of it from the device.

Optical character recognition

Scanned pages are recognised on the device — Apple Vision on iPhone, iPad, and Mac, and Windows.Media.Ocr on Windows. Neither the page image nor the recognised text is sent to us or to any recognition service of ours.

iCloud, if you switch it on

On iPhone and iPad you can turn on iCloud synchronisation for your reading and research records, and separately for your EPUB and PDF files. When you do, that data is stored in your own iCloud account through Lexfolio’s CloudKit container — it does not pass through a server of ours. Because iCloud syncing is a system service, it may run in the background while the app is closed, on the operating system’s schedule.

Dictionary packs and local search indexes are never synchronised; they are rebuilt on each device.

Synchronisation is off until you enable it, and Windows has no iCloud path at all.

The things that leave only when you ask

Online dictionary links. Lexfolio’s bundled dictionaries work with no network connection. A web page opens only when you tap an HTTPS link yourself.

Dictionary pack downloads. Optional packs are fetched only after you choose one.

The grounded research assistant. This is off until you supply your own provider endpoint, model, and API key — Lexfolio has no key of its own. Before every request it shows you the provider’s host and the exact number of excerpts being sent, and waits for you to confirm. A request carries your question and only the excerpts you checked: never your whole library, never books you did not select. Your API key is kept in the Apple Keychain or Windows Credential Manager, and never in the app’s database, in iCloud, in logs, in backups, or in a .lexfolio package.

The in-reader AI chat panel. This opens the ChatGPT, Claude, or Gemini website you chose. Choosing AI Chat copies the selected passage and its work title, author, edition, and language to your device clipboard — Lexfolio does not type or submit anything for you. The text reaches that service only when you paste it and send it yourself. Opening the site is a normal web request to that third party, and their own account, cookie, privacy, and retention rules apply from that point on. You can always use your external browser instead.

.lexfolio research packages. These contain checksummed project metadata and portable references. They deliberately exclude the book files themselves, and you choose where each package is saved or who receives it.

Purchases

Lexfolio is free for seven days, then unlocked by a single purchase. The purchase is made with Apple; we never see your payment details. The app verifies the purchase itself, on the device, and that is what decides whether Lexfolio is unlocked.

So that we can see how the app is selling, a record of each purchase is also sent to RevenueCat, a purchase-reporting service. That record is attached to an anonymous, randomly generated identifier — it is not linked to your name, your email address, or anything in your library, and it is not used to track you across other companies’ apps or websites. RevenueCat plays no part in unlocking the app or restoring a purchase; if it were unreachable, Lexfolio would work exactly the same. RevenueCat’s handling of this data is described in RevenueCat’s Privacy Policy.

The seven-day trial is kept in your device’s Keychain, which is why deleting and reinstalling the app does not start it again.

Third parties

When you send a request to a provider endpoint you configured, or open a chat service in the reader, that company’s own privacy and retention terms govern what they do with it. Lexfolio is not a party to that exchange and never sees it.

Children

Lexfolio is rated 16+ (17+ on iOS versions before 26) because the in-reader chat panel can open third-party websites you choose.

Changes and contact

If this notice changes, the date at the top changes with it. Questions about anything above are welcome at the address shown on this page.