Privacy Policy
Effective October 24, 2026
Hotaru works fully without an account. Without one, your decks, cards and review history stay on your device and JJ Software receives none of them.
Flashcards are made by Apple Intelligence on your device. Only if your device can't run Apple Intelligence, and you allow it, is the material you choose sent to a cloud AI model to write cards — for that request only, never stored or used for training (section 6).
No ads and no tracking. The app sends anonymous usage counts (such as "finished a study session") with a random ID, which you can turn off in Settings (section 7).
Hotaru is developed by JJ Software ("we", "us"). This policy covers the Hotaru app for iPhone and iPad, its widgets, Control Center control and Siri shortcuts, and the shared-deck pages at hotaru.jjsoftware.online.
Questions about this policy or your data: contato@jjsoftware.online.
Everything you create is stored in a local database on your device (Apple's SwiftData):
Widgets read a small summary (how many cards are due) through an App Group, a space Apple provides for an app's own components on the same device.
If you choose Sign in with Apple, Hotaru creates an account so your decks sync across your devices. We then store:
This data is stored with PlanetScale (database) and served by Cloudflare (hosting) on our behalf. Like any web service, requests include an IP address, used only for security and abuse prevention and kept in short-lived logs.
Shared decks: if you create a link for a deck, that deck's title, description and cards — never your progress — and your first name become visible to anyone with the link, until you stop sharing it.
Reports: if you report a shared deck, we store the reason, any details you write and a one-way hash of your account or IP address (so one person counts once), and email them to our moderator. Reports are kept for up to a year, and the deck's owner never sees who reported it. Blocking a sharer is stored only on your device.
Creating cards from text, photos, scans or PDFs, checking typed answers, explaining and improving cards use Apple's on-device model. Your material is processed on your device and is not sent to us.
If the app is configured to use Apple's Private Cloud Compute for very long documents, Apple processes that request in its private cloud and does not keep it; we never receive it.
Speaking practice uses the microphone only while you answer. Your speech is turned into text on your device; it is never recorded, sent to us or kept.
The camera is used only when you scan pages, and photos or PDFs only when you pick them. Images and documents are read on your device to make cards and are not stored by the app afterwards.
On devices that can't run Apple Intelligence, Hotaru can write cards with a cloud AI model instead. It's used only after you allow it, requires signing in, and can be turned off in Settings › Apple Intelligence.
When you use it, the material you chose (text, or images of pages) is sent to our server at hotaru.jjsoftware.online, which forwards it to an AI model through OpenRouter, Inc. Requests are routed only to model providers that do not store prompts or use them for training. We do not store your material; we keep only a count of requests per account per day to prevent abuse.
To understand how Hotaru is used and what to improve, the app sends anonymous events to PostHog, Inc. (hosted in the United States) — for example "created a deck", "finished an AI creation", "finished a study session", "viewed the Hotaru Pro screen" or "started a subscription".
Each event carries only a random ID created on install, the app version, the device language, and a few fixed values such as which plan was chosen or how many cards were reviewed. It never includes your cards, notes, deck titles, your account, your Apple ID or any advertising identifier, and it is not linked to your identity or used for advertising.
You can turn this off anytime in Settings › Privacy › Share Anonymous Usage; that also deletes any events not yet sent and the random ID.
Hotaru Pro is bought through Apple. We never see your payment details. The app checks your subscription status with Apple on your device.
Glow packs are also bought through Apple. To add the Glow to your account, the app sends us Apple's signed record of that purchase, and we keep its transaction ID, the pack and the date with your account. We never see your payment details.
Apple also notifies our server of purchase events — a trial starting, a renewal, a cancellation, a refund, a Glow pack — so a refunded pack stops counting and we can follow sales. Each notice has the product, the price, the country of your App Store, dates and Apple's transaction IDs; no name, email or payment details, and it isn't linked to your Hotaru account (except a Glow pack, which belongs to the account that bought it). We keep them to run the service and for our records.
To understand how subscriptions do — trials that turn into a subscription, renewals, cancellations, refunds — the app also shares your App Store purchase records with RevenueCat, Inc. (United States), which processes them for us. It receives a random ID created by the app, the products, prices, dates, your App Store country, Apple's transaction IDs, and the device model and system version; never your payment details, your cards or your Hotaru account. While Share Anonymous Usage is on, that ID is linked to the anonymous usage ID in section 7, so we can see which screens lead to a subscription.
Hotaru shows no ads, does not track you across other companies' apps or websites, and we never sell or rent your data.
Data on your device stays until you delete it or the app.
Settings › Delete Account removes your account, synced decks, review history and shared links from our servers immediately, and revokes Sign in with Apple. Signing out lets you keep or remove the copy on your device. Server logs expire within 30 days.
Depending on where you live (for example under Brazil's LGPD, the EU/UK GDPR or California law), you can ask to access, correct, export or delete your personal data, and object to its use. Most of this is available directly in the app; for anything else, write to us and we'll answer within 15 days.
Hotaru is a general study app and is not directed at children under 13. We don't knowingly collect personal data from them; the app works fully without an account.
We'll update this page and its effective date when this policy changes, and tell you in the app about material changes. JJ Software · contato@jjsoftware.online · jjsoftware.online.
Hotaru · Effective October 24, 2026