Bookfolio Privacy Policy

Last updated: 16 September 2026

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Bookfolio is a reading tracker. This page describes what it does with your data. It is longer than we would like, because the app talks to Google in several ways, and each one deserves a plain sentence.

In one sentence

There is no Bookfolio server and no Bookfolio account. Your library lives on your phone. Copies of it leave the phone in three cases: Android’s own backup, which is on by default; Google Drive sync, if you turn it on; and telemetry, if you turn it on. Searching for a book sends your search terms to Google Books, or to Open Library when Google Books has nothing.

What the app stores, and where

Everything is stored locally on your device, in files that only Bookfolio can read:

Data	Where
The books you add: title, authors, publisher, year, ISBN, categories, summary, cover address	local database (`bookfolio.db`)
Your reading: status (To Read, Reading, Read, DNF), start and finish dates, page progress, rating, notes, wishlist, owned	same database
Your collections	same database
Your activity log	same database
Your recent searches	same database
Your settings: theme, accent colour, reminders, yearly goal, telemetry choices	local preferences (`bookfolio_prefs.xml`)
The Google authorization token, if you connected Google	an encrypted store, separate from the files above
Cover images, once downloaded	the app’s image cache

None of this is transmitted to the author of the app, nor readable by him.

What leaves the device, and when

Six cases. The first is not triggered by you, which is why it comes first.

Android’s automatic backup. Android copies bookfolio.db and bookfolio_prefs.xml to the backup space attached to your Google account, as it does for the other apps on your phone, and it carries them across when you transfer to a new device. That is what gives you your library back when you reinstall the app or change phones.

Android does it, not Bookfolio. The app only declares which files are worth backing up. The Google authorization token is not among them.
It is encrypted with your device lock code, since Android 9. Google holds the copy without being able to read it, and the author of Bookfolio has no access to it.
It is on by default, and you can turn it off, in Android’s settings, under Google then Backup, for the whole device or for Bookfolio alone. Settings › Sync & data › “Back up now” only asks Android to run the backup it would run anyway.

Searching for a book. When you type a title, an author or an ISBN, or scan a barcode, the app sends the search terms to the Google Books API, and to Open Library when Google Books returns nothing. Requests to Google Books carry the app’s package name and signing certificate, which is how Google restricts the API key to this app; they carry nothing about you. Cover images are then downloaded from Google Books or Open Library. Barcode recognition happens on the device: no image or video leaves it.

Google Drive sync. If you connect Google, the app asks for exactly one authorization: drive.appdata, the private folder that Google Drive keeps for each app. That authorization gives Bookfolio no access to the rest of your Drive, and no identity data: not your name, not your e-mail address, not your profile picture. Two things are written to that folder:

a complete archive of your library and settings (bookfolio.db and bookfolio_prefs.xml), so that a new device can restore it;
a per-book sync file: ISBN, status, dates, progress, rating, wishlist, owned, notes, plus title, authors and cover address so that another device can recognise the book. It is merged in both directions between your devices.

The token that authorizes this is stored encrypted on the device. Settings › “Disconnect Google account” deletes that token from this device; it does not delete what is already in your Drive. To delete that, open Google Drive’s settings, Manage apps, and delete Bookfolio’s hidden app data.

Bookfolio no longer writes to your Google Books shelves. That synchronization was retired in April 2026.

Telemetry, if you turn it on. Bookfolio includes two Google libraries, Firebase Analytics (which screens are opened, which features are used, which version runs) and Firebase Crashlytics (crash diagnostics). Both are off by default: the app ships with collection disabled, and nothing is sent until you switch them on, during onboarding or in Settings › Sync & data. You can switch them off at any time. The events the app sends contain no personal data and nothing about your books. What Firebase does with them, and for how long it keeps them, is governed by Google’s Firebase privacy policy. The advertising identifier is removed from the app entirely, whatever you choose.

A tip or the supporter badge. Payment is handled by Google Play, not by Bookfolio. You give your payment details to Google; the app never sees them. Bookfolio receives only the confirmation that the purchase went through, and reads your supporter status back from Google Play. What Google collects on that occasion is covered by Google’s own privacy policy.

A review on the Play Store. After a while, the app may offer once to rate it. The exchange happens between your device and Google Play.

Permissions, and why they exist

The ones you would see if you inspected the app:

Permission	Reason
Camera	Scanning barcodes, only while the scanner is open. Optional: typing the ISBN finds the same book, and a device without a camera can install the app.
Notifications	Reading reminders: the book in progress, the wishlist, a weekly summary. Local, optional, and off unless you turn them on.
Internet, network state	Book search, cover images, Google Drive sync.
Vibration	A short buzz when a barcode is read.
Google Play billing	Tips and the supporter badge.

The advertising identifier permission that Firebase would normally add is explicitly removed from the app.

What Bookfolio does not do

No ads, no ad network, no advertising identifier.
No selling or sharing of data with third parties.
No Bookfolio account, no e-mail address asked for.
No location, no contacts, no access to your photos; the camera shows only a live preview and records nothing.
No telemetry unless you turn it on.

Children

Bookfolio is not directed at children under 13 and does not knowingly collect data from them.

Your rights

Your data is on your device and, if you chose so, in your own Google account. You control it directly:

Access and correction: everything is visible and editable in the app.
Deletion on the device: uninstalling the app deletes the database, the preferences and the cache. If Android’s backup is on, an earlier copy may survive until the next backup replaces it.
Deletion in Google Drive: from Drive’s settings, Manage apps, delete Bookfolio’s hidden app data.
Telemetry: switch it off in Settings; requests about data already sent to Firebase go through Google.

There is nothing to ask us for, because we hold nothing.

Changes

This policy changes when the app changes. The date at the top is authoritative; the full history is in the project’s repository.

Contact

Write to mferyapps@gmail.com.