ZiZ is a training journal for Brazilian Jiu-Jitsu practitioners, developed and operated by ZiZai (Beijing) Tech Co., Ltd ("we", "us"). This policy explains what the app does with your information. We have tried to write it in plain language rather than legal boilerplate, because a privacy policy you can't understand isn't much of a promise.
1. The short version
Your notes are yours, and they stay on your device. Every card you write, every connection you draw, every photo or video clip you attach — all of it is stored locally on your phone or computer. We do not upload it, we cannot read it, and there is no account to sign up for.
The app makes exactly one kind of network request in normal use: verifying that you actually bought it. That request carries a purchase receipt and nothing else. Section 5 describes it in detail.
2. What we collect
2.1 The content you create — collected by us: none
Your cards, notes, technique breakdowns, progress markers, canvas layouts, and any images or video clips you import are written to your device's own app storage. They are never transmitted to us. This is not a policy choice we could quietly reverse — the app has no code path that uploads your notes anywhere.
2.2 Purchase information — the minimum needed to verify a purchase
ZiZ is paid software with a free trial. When you buy it, Google Play (or another store, depending on where you downloaded the app) issues a purchase token or receipt. The app sends that token to our verification service so we can confirm the purchase is genuine and unlock the full version — including when you reinstall the app or move to a new device.
What that request contains: the purchase token or transaction identifier, the product identifier, and the platform. It does not contain your notes, your name, your email address, or any content you created. We do not receive your payment card details at any point; the store handles payment entirely.
2.3 Store-provided statistics
Google Play gives every developer aggregate, anonymized statistics — install counts, crash reports, country-level breakdowns. We see those the same way any developer does. They are not linked to you as an individual, and we do not combine them with anything else.
The app itself contains no analytics SDK, no advertising SDK, and no crash-reporting SDK. If we ever add anonymous usage statistics, we will say so in this policy and provide a way to turn them off.
3. What we never do
- We do not sell, rent, or trade your personal information — to anyone, for any price.
- We do not show ads, and we do not track you for advertising purposes.
- We do not upload your notes or media in the background.
- We do not ask for permissions the app doesn't need. ZiZ requests no runtime permissions on Android beyond network access.
- We do not build a profile of you, because we do not have the data to build one from.
4. Where your data lives
Your notes live in the app's private storage on your device. A few consequences worth knowing:
- Uninstalling the app deletes your data. Back up anything you care about first — the app has an export function for exactly this.
- We have deliberately disabled Android's automatic backup, including device-to-device transfer. Your data will not be copied into your Google account without your involvement. Backup is something you do on purpose, using the tools below — not something that happens to you.
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Encrypted backup files (
.zizbak) are encrypted with a key derived from a passphrase you choose. We never receive the passphrase or the file, which also means we cannot recover it for you if you forget it. That tradeoff is intentional. - Optional folder sync lets you point the app at a folder you control — an iCloud Drive folder, a synced directory on your computer, wherever. Your data is encrypted before it is written there. It travels through your cloud provider, not ours, under your account and their privacy policy.
5. Purchase verification and international transfers
We are a company based in Beijing, China. For users outside mainland China, purchase verification is handled by servers hosted outside mainland China; the requests described in section 2.2 go there. Purchase records may be accessed by our team in China for customer support, refund handling, and accounting. Because your notes never leave your device, they are never subject to any international transfer at all — the only thing that crosses a border is a receipt.
All verification traffic uses HTTPS. If verification is temporarily unavailable — you're offline, or our service is down — the app continues to work normally using its stored verification status. We do not lock you out of your own notes because a server didn't answer.
6. Third-party services
App stores. Downloading and paying for ZiZ happens through Google Play or another store, each governed by its own privacy policy. We receive only what section 2.2 describes.
Video links you add. You can attach links to instructional videos on YouTube, Bilibili, or elsewhere. Tapping one opens that platform, at which point that platform's privacy policy applies. We do not proxy, log, or analyze these links — they are just text in your own notes.
7. Security
Because your notes are stored locally, their security rests largely on your device's own protections. We recommend using a screen lock and keeping your operating system updated.
For the data we do protect directly, we use standard, well-reviewed cryptography rather than anything homegrown: encrypted backups use PBKDF2 key derivation (250,000 iterations) with AES-GCM-256, via the platform's own Web Crypto implementation. Network requests use HTTPS.
No system is perfectly secure, and we won't claim otherwise. What we can say is that the amount of your data we hold is close to zero, which is the most effective security measure available to us.
8. Children
ZiZ is not directed to children under 13, and we do not knowingly collect personal information from them. Brazilian Jiu-Jitsu is a full-contact sport; minors should train under qualified supervision, and should use this app with a parent's or guardian's knowledge and consent. If you believe a child has provided us with personal information, contact us and we will delete it.
9. Your rights
For the content you create, you hold the controls directly — no request to us is required, and none would help, since we don't have the data:
- Access and portability: export your data at any time from within the app.
- Correction: edit any card or note directly.
- Deletion: delete individual items in the app, erase everything from the settings screen, or uninstall the app.
For purchase records, contact us at cs@zizai.tech to request access or deletion. Note that we may need to retain a minimal transaction record to comply with tax and accounting law, and that deleting a purchase record may prevent you from restoring your purchase later.
Depending on where you live, you may have additional statutory rights — including under the GDPR if you are in the European Economic Area or the UK, or under state privacy laws in the United States. We honor these requests regardless of where you live. We will not discriminate against you for exercising any privacy right.
10. California residents (CCPA / CPRA)
If you are a California resident, you have specific rights regarding your personal information. Here is how they apply to ZiZ:
- Categories we collect. Commercial information, in the form of purchase records (section 2.2). We do not collect identifiers, geolocation, biometric information, browsing history, or inferences about you.
- Sources. Directly from the app store when you make a purchase.
- Purpose. To verify and restore your purchase, provide support, and meet accounting obligations.
- Sale or sharing. We do not sell your personal information, and we do not share it for cross-context behavioral advertising. We have not done so in the preceding twelve months, and we have no plans to. Because we do not sell or share, there is no opt-out link to provide.
- Sensitive personal information. We do not collect it.
- Your rights. You may request to know, delete, or correct the personal information we hold, and to receive it in a portable form. Submit requests to cs@zizai.tech; we will verify your request using your purchase token and respond within the timeframe the law requires.
- No discrimination. Exercising these rights will never result in a degraded app, a different price, or a denial of service.
11. Data retention
Your notes are retained on your device for exactly as long as you keep them there — we have no say in it. Purchase records are retained for as long as your purchase remains valid (a lifetime purchase means we keep the record so you can restore it), plus any period required by applicable tax and accounting law.
12. Changes to this policy
We may update this policy as the app evolves. When we do, we will change the date at the top of this page. For material changes — particularly anything that would expand what we collect — we will notify you in the app before the change takes effect, rather than quietly editing this page.
13. Contact us
Questions, requests, or concerns about this policy or your data: cs@zizai.tech. We read every message.