Privacy policy

Hibi has no accounts and no account server. What you study lives on your device and stays there: every character you have seen, every review, your streak, your schedule, your setup answers. No character you have learned, and no character you have struggled with, is ever sent anywhere.

Two things leave the device on their own: the app asks a subscription service whether you have paid, and it counts how the app is used so we can see where people get stuck. A third leaves only if you type it in — your email address, in the optional field setup puts in front of you. This page describes all three.

What stays on your device

Your learning progress. Every character you have seen, every review, your streak, and your schedule live in a database file inside the app's private container on your iPhone or iPad. It is shared with the Hibi widget through an Apple app group, which is a folder only Hibi and its widget can read.

Your onboarding answers. How you heard about Hibi, your level, your pace, and which scripts you chose are stored on the device so the app can build your plan and the widget can show the right character.

Your email address, if you gave one. The address you typed on the optional email screen ("Master Japanese Kana") during setup, or in Settings, is kept beside your other answers so the app can show it back to you and change it. Leaving the field empty means there is nothing to keep. It is also sent to one company, described below under What leaves your device, because sending it is the point of giving it.

There is no account, and nothing to sign in to. Hibi never had a password, and as of this version it has no sign-in either. Earlier TestFlight builds asked for Sign in with Apple, stored a hashed version of the identifier Apple returned, and stored the name and email Apple passed along if you allowed it. That screen is gone, and so is everything it wrote: the first time you open this version, Hibi deletes the hashed identifier, the name and the email from this device's keychain, including any copy that had reached iCloud Keychain. None of it was ever sent to us, and now it is not on the device either.

Apart from the email address, none of this is uploaded. There is no Hibi account server to upload it to, and none of it syncs to iCloud. If you have device backups switched on, Apple's own backup rules apply to whatever they cover, and those are governed by Apple's privacy policy rather than this one.

What leaves your device

Hibi uses Adapty to check your subscription and to fetch the layout of the subscription screen. Adapty is a subscription infrastructure company based in the United States. It is contacted about paying, and — only if you chose to give one — about your email address. It is never contacted about studying.

What Hibi sends it:

• An anonymous identifier. Adapty generates a random ID for your install. Hibi never gives it your name, your Apple ID, or a login. The optional email address below is the only thing you typed that it gets.
• Purchase information. When you subscribe, restore, or renew, the App Store transaction goes to Adapty so it can verify the receipt with Apple and tell the app whether your subscription is active. This is which plan and when, not how you paid.
• Your email address, but only if you typed one in. The optional email screen in setup — "Master Japanese Kana" — offers the field, Settings has the same field under Email updates, and so does the subscription screen, under the same name, so that changing or removing an address never depends on having subscribed. If you type an email into the optional field, it goes to Adapty (the company that runs our subscriptions) and sits on the same anonymous profile as your purchase state. We use it to send study tips and product updates. That profile is where we read and export the list from. Nothing rides along with it: no name, no Apple ID, and nothing about what you study or how you are doing at it. Every screen and every feature of Hibi behaves the same whether you give it or skip it. It is not used to track you, not sold, and not shared with anyone else. Skip the field and no email address exists anywhere in this app or at Adapty.
• Basic technical context that comes with any network request, such as your country, the app version, and the operating system version.

What Hibi never sends it: which characters you have learned, your streak, your review history, your onboarding answers, or anything else you typed.

Adapty's own privacy policy is at adapty.io/privacy.

Your payment details never touch the app or Adapty. Payment is handled entirely by Apple.

Usage counts

Hibi uses PostHog to count how the app is used, so we can see where people get stuck and fix it. PostHog is a product analytics company; Hibi's data is stored on its servers in the United States. This is the only place anything about studying leaves the device, and we have deliberately kept it to counts rather than content.

What Hibi sends:

• Which screen you reached in the setup flow, so we can see where people give up.
• Whether the subscription screen was shown, and whether it was dismissed.
• That a character was practised, with how you rated your recall (again, hard, good, easy), how many milliseconds you took, which day of the course it was, and which kind of card it was (for example hiragana, katakana, or a sound rule).
• That a day was completed, that the review queue was cleared and how many cards were in it, that the widget was tapped, that the app was opened, and when you reach a streak milestone.
• That you traced a character, and how many strokes it had. Not the character, and nothing about what you drew: the tracing you do is never recorded, transmitted or looked at.
• That you finished setting up, with the level and the pace you chose, how many characters were marked as already known, and how many are left to learn. This is how we tell whether people are running out of material too quickly, which is the single most useful thing we can know.
• That you reached the end of the course, and how many days it took.
• That you opened Hibi and had nothing due, at most once a day.
• Basic technical context that comes with any network request: the app version, your device model and iOS version, your language and time zone, and an approximate location (country, sometimes city) that PostHog derives from your IP address. The IP address itself is how the internet works, not something Hibi adds; the derived location is how we know which countries Hibi is being used in.

What Hibi never sends: which character it was. No card ever leaves the device carrying its identity. We can see that someone found a day-14 hiragana card hard; we cannot see that you struggle with ぬ, and neither can PostHog. Which characters you find difficult is exactly the thing a learner would mind sharing, it is not needed to answer any question we have, so it is not sent.

Also never sent: your name, your Apple ID, or anything you typed. That includes the optional email address: if you gave one it went to Adapty and nowhere else, it is not attached to any event, and PostHog has no way to reach it. Of the setup questions, only the level and the pace are sent, because those two decide how much material you have. Which specific characters you ticked as already known is never sent, and neither is why you are learning Japanese or how you heard about Hibi.

There is no identifier that points to you. PostHog assigns a random ID to the app installation. Hibi never calls PostHog's identify function, so that ID is never joined to a person, an account, or your subscription. Reinstalling the app produces a new one.

We have also turned off the two features that would collect far more than the list above: autocapture is off, so PostHog does not silently record every tap and screen, and session replay is off, so no recording of your screen is ever made.

PostHog's own privacy policy is at posthog.com/privacy.

Turning it off

Open Settings inside Hibi and switch off Share anonymous usage data. Nothing is sent from that point on. The app works exactly the same either way, and nothing is gated behind leaving it on.

Tracking

Hibi does not track you. There is no advertising SDK and no attribution tool. Hibi does not use the Advertising Identifier, does not share data with data brokers, and does not collect data linked to your identity for advertising or measurement. You will never see an App Tracking Transparency prompt from Hibi, because there is nothing to ask about.

The usage counts described above are not tracking. They are not linked to your identity, they are not combined with data from anywhere else, and they are used to improve Hibi and nothing else.

Children

Hibi is rated 4+ and contains no objectionable content, no chat, no user-generated content, and no advertising. The data that leaves the device on its own is the anonymous subscription information and the anonymous usage counts described above, and both are the same for every user regardless of age. Neither is used for advertising and neither is linked to a person. The only other thing that can leave is an email address, and only because someone chose to type one in; nothing in the app asks a child for anything else, and nothing is withheld from anyone who leaves that field empty.

Third-party components

Besides Adapty and PostHog, Hibi is built with two open source libraries that run entirely on the device and send nothing anywhere: GRDB (MIT), the local SQLite layer, and swift-fsrs (MIT), the spaced repetition scheduler.

The Hibi widget links neither Adapty nor PostHog. It reads one value out of the app group folder and sends nothing anywhere.

Learning content is derived from open data sets: JMdict and KANJIDIC2 (Electronic Dictionary Research and Development Group, Creative Commons), KanjiVG (CC BY-SA 3.0), and Tatoeba (CC BY 2.0). These are compiled into the app at build time. The app does not contact them at runtime.

Deleting your data

Delete the app. The database and the app group folder go with it, and that is all of your study history.

The keychain entries an older build left behind are already handled. Hibi writes nothing to the keychain any more, and the three items Sign in with Apple used to write are deleted the first time you open this version, on the device and in iCloud Keychain both. There was never anything on our side to delete, because we never received them. If you last used Hibi before this version and never open it again, iOS decides when those items go: an app is not notified when it is deleted, and keychain items can outlive an uninstall until the system clears them. Opening Hibi once clears them immediately. You can also revoke Hibi's access to your Apple ID at any time in Settings, under your name, then Sign in with Apple — the app no longer uses it, and revoking has no effect on anything Hibi does.

For the usage counts held by PostHog, there is nothing that identifies you, which is the point and also the limitation: because the installation ID is random and never joined to a person, we cannot find "your" rows to delete. Switching off Share anonymous usage data in Settings stops any further counts immediately, and deleting the app ends them permanently.

For the email address, if you gave one: open Settings inside Hibi, tap Email updates, and choose Remove email. That takes effect immediately — the address is erased from the device, we stop using it for anything, and your Adapty profile is marked as withdrawn so it drops out of every list we send to. Marking the profile is not the same as erasing the address from it, and Adapty's app-side API gives us no way to blank a stored email, so the app cannot do the erasing itself. Email hibiteam.app@gmail.com and ask us to delete your address, and we will delete the profile that holds it. You do not have to give a reason, you do not have to still have the app, and you can ask whether or not you used Remove email first.

For the subscription record held by Adapty, email hibiteam.app@gmail.com and we will have it deleted. Because the identifier is anonymous, tell us roughly when you subscribed and which plan, so we can find it. Deleting that record does not cancel your subscription; cancel that in Settings, under your Apple Account, then Subscriptions.

Changes

If this policy changes, the date beside the title changes with it. If a future version of Hibi ever collects anything beyond what is listed here, that will be stated on this page in plain language before the version ships.

Contact

hibiteam.app@gmail.com