Foxleaf Privacy Policy
Foxleaf is operated by TRON Technologies LLC ("Foxleaf", "we", "us").
This policy explains what the Foxleaf service — the mobile apps and the web portal at foxleafapp.com — collects, why, and who processes it.
Effective: July 21, 2026 · Last updated: July 21, 2026
Contact: support@foxleafapp.com
The short version
Foxleaf turns audiobooks you own into illustrated audiobooks. The transcription and the pictures happen on your device — your audio is turned into text on your device, the illustrations are generated on your device, and your audio is never sent to any transcription or image service. The transcript and the generated images stay on your device. (Audio you upload through the web, or that syncs between your devices, is held in our secure storage until your device downloads it, then deleted — see "Purchased-audio relay" and "The web portal" below.)
What we do send off the device is narrow and purposeful: your account email (to sign you in), short portions of a book's transcribed text (to generate each illustration), and your purchase details (to take payment and unlock a book). The Foxleaf apps use no analytics SDKs, crash-reporting SDKs, advertising, or third-party trackers. We do not sell your data.
What stays on your device (and never leaves)
- Your audiobook files. Audio you import stays local. (Purchased audio may be relayed once between your devices — see "Purchased-audio relay" below.)
- Transcription. Speech-to-text runs entirely on your device (WhisperKit on iOS, whisper.cpp on Android). Transcripts are not uploaded.
- Illustrations. Images are generated on your device (Apple Neural Engine / on-device Stable Diffusion). The generated images are saved locally and are never uploaded.
What we collect and send off the device
| What | Where it goes | Why | When |
|---|---|---|---|
| Account email (and password, to our auth provider) | Firebase Authentication (Google) | Create and secure your account | Sign-up / sign-in |
| Account identifier (uid) | Firebase (Google) | Tie your library and purchases to your account | Signed-in use |
| Portions of transcribed book text — the passage at your current listening position plus a few surrounding passages | Google (Gemini), via our illustration service | Generate a fitting illustration prompt for the current part of the book | About once per minute of listening, whether or not an illustration is displayed |
| Purchase details — book title, author, duration, a content hash, and (if you provided it) a rights attestation | Our payment/verification service, then Stripe (Android) or Apple (iOS) | Take payment and unlock the book on your account | When you buy a book |
| Catalog browsing — search terms, page, genre, language (not tied to your identity) | Our catalog service, which proxies public-domain sources (LibriVox / Internet Archive) | Show and download public-domain books | Browsing the catalog |
About the book text we send. To illustrate a book, Foxleaf sends the text near your current position — the current passage plus roughly the preceding three and the following one — to Google's Gemini model to produce an image description. This happens approximately once per minute of listening, whether or not an illustration is displayed for that passage — the illustration-frequency setting controls how often an image is shown, not how often text is processed — and is inherent to how illustrations are made. We send only these rolling passages and prompt text; we do not send your identity, email, or the book's purchase record to the image service, and the generated image and full transcript stay on your device. When you first add a book, a one-time setup lookup may use Gemini's Google Search feature to fetch facts about the book, so that query text can reach Google Search.
Who processes your data (third parties)
- Google — Firebase (authentication, database, file storage, cloud functions) and the Gemini model that turns book passages into image prompts. For the one-time book-setup lookup, Gemini's Google Search grounding may be used, so that query text can reach Google Search. Gemini receives only prompt text and passages — not your identity, email, or purchase record.
- Stripe (Android payments) — receives your email, book purchase details (title, author, duration, price, a content hash, rights attestation), and processes your card. Card details are handled by Stripe's own checkout; Foxleaf never sees or stores your card number.
- Apple (iOS purchases) — handled by the App Store; Foxleaf verifies Apple's signed receipt server-side.
- Model delivery — on iOS, the on-device transcription model is downloaded on first use from Hugging Face, and the on-device image-generation model from Google (Firebase Storage). On Android, the on-device models are provided locally and are not downloaded from a third party. These downloads carry your device's IP address (as any download does) but no personal data.
- Public-domain sources (LibriVox / Internet Archive) — reached through our catalog proxy for free books; no account data is attached.
- EmailJS — if you use the contact form on foxleafapp.com, your name, email, and message are relayed to us through EmailJS. Used only to receive and reply to your message.
Foxleaf uses no analytics or measurement SDKs, crash-reporting SDKs, advertising or ad-attribution SDKs, or behavioral trackers, and the website sets no advertising or analytics cookies. (Verified in both the app and website source.) The website loads fonts and icons from third-party content-delivery networks, which — like any web request — receive your IP address.
The web portal (foxleafapp.com)
You can upload and manage books you own through the web portal. When you upload audio, it is stored in our Firebase file storage under your account (you are signed in as yourself); the app then relays it to your device and deletes the relay copy. Before uploading or buying, you confirm your rights to the audio (see the Terms of Service). The portal uses your Foxleaf sign-in and essential login/session storage only.
Purchased-audio relay
When you buy a book whose audio you provided, that audio is placed in our file storage under your account so it can reach your other devices. It is held until your device downloads it, then deleted from the relay, and is used only to deliver your purchase to you.
Payment and purchase records
When you buy a book, our service records the purchase on your account so it's recognized across your devices. The record — stored under your account and keyed by a content hash of the book — includes the book's title and author, its duration, the price paid and tier, a payment or transaction identifier, timestamps, the original filename and audio format, the purchase source (Apple or Stripe), and, for audio you uploaded, your rights attestation. It does not include payment card data, which is handled solely by Stripe or Apple.
To meter illustration usage, our service also stores under your account a list of one-way hashes of the passages processed for illustration — not the passage text itself — used only to count usage.
Retention and deletion
We keep account and purchase data for as long as your account exists. The purchased-audio relay copy is deleted after it reaches your device.
Deleting your account. You can delete your account and its associated data — your authentication record, your library and purchase documents, any relay copies of your audio, and your usage records — at foxleafapp.com/delete-account (and from within the app once in-app deletion is available). See Delete your account for details. Note: we may retain limited transaction records where required by law (for example, tax and financial-record obligations) even after account deletion.
Your rights
Depending on where you live, you may have rights to access, correct, or delete your personal data, and to obtain a copy. Contact support@foxleafapp.com to exercise them.
Children
Foxleaf is a general-audience app and is not directed to children under 13. We do not knowingly collect personal information from children under 13.
AI-generated content
Illustrations are machine-generated by an AI model from the book's text. They may not accurately or appropriately represent it, are not authored or endorsed by us, and — because they are generated on your device from the book you provide — are not pre-screened by us. They are created for your personal listening experience. See the Terms of Service.
Changes to this policy
We may update this policy; we will revise the "Last updated" date and, for material changes, provide notice in the app or on foxleafapp.com.
Contact
TRON Technologies LLC — support@foxleafapp.com