Privacy Policy
Last updated: 20 October 2026
This policy explains what information Reader ("the app") uses, why, and the choices you have. The app is made by SLUX LLC ("we", "us"), 30 N Gould St Ste R, Sheridan, WY 82801, United States. Questions: hello@sluxstudio.com.
The short version
- No ads, no advertising trackers, and we do not sell your information.
- When you tap a word, the sentence it is in is sent to Google's Gemini AI to produce the explanation.
- If you sign in, your books, saved words, highlights, reading positions and settings are stored in your account so they sync between your devices.
- You can delete your account and its data from inside the app at any time.
Using the app without an account
When you first open the app you are a guest. Your books, words and highlights stay on your device. The app still creates an anonymous account identifier with Firebase (a Google service) so that it can count your daily AI requests and protect the service from abuse. This identifier is not linked to your name or email.
Signing in
You can sign in with Google (and, where offered, with Apple). We receive your name, email address and an account identifier from the sign-in provider. We use them only to create and secure your account and to keep your data in sync. Signing in moves your guest data into your account.
Information we store for signed-in users
| Information | Why |
|---|---|
| Book files you import (EPUB, and books converted from PDF on your device) | So your library is available on all your devices |
| Saved words and highlights | To show and sync your vocabulary and highlights |
| Reading positions and app settings | To open each book where you left off on any device |
| Sentences you looked up and their AI explanations | So the same sentence is not sent to the AI again, which keeps the app fast and limits cost |
| A daily count of AI requests | To apply the daily allowance and prevent abuse |
This information is stored with Google Firebase (Cloud Firestore and Cloud Storage) and is only accessible to your account and to us for operating the service.
AI word explanations
When you tap a word, the app sends the sentence containing it, and which word you tapped, to Google's Gemini model through Firebase AI Logic. Google processes this text to return the explanation, under Google's terms for that service. We do not send your name or email with these requests. Do not tap words in passages that contain information you would not want processed this way.
Information we do not collect
- We do not use analytics or advertising SDKs, and we do not track you across other apps or websites.
- Reading aloud runs on your device; the text is not sent to us.
- PDF files are converted on your device. Purchases are handled by Apple; we never see your payment details.
Service providers
- Google (Firebase Authentication, Cloud Firestore, Cloud Storage, App Check, Firebase AI Logic with Gemini, Google Sign-In) to run accounts, sync and AI explanations.
- Apple to distribute the app, process purchases and, where offered, Sign in with Apple.
These providers may process information in the United States and other countries.
Keeping and deleting your information
We keep your information while you have an account. You can delete your account in the app's account settings. This permanently deletes your synced books, words, highlights, positions, settings, saved explanations and AI usage records from our servers, along with the data on that device. You can also email us to ask for a copy of your information or for its deletion.
Children
The app is not directed to children under 13, and we do not knowingly collect information from them. If you believe a child has given us information, contact us and we will delete it.
Your rights
Depending on where you live, you may have the right to access, correct, delete or export your information, or to object to how it is used. Contact hello@sluxstudio.com and we will respond within 30 days.
Changes
If we change this policy we will update the date above, and tell you in the app if the change is significant.