Privacy Policy
1. Who we are
Beijing Yixing Tianxia Technology Co., Ltd. (北京翊行天下科技有限责任公司) is a company registered in Beijing, China. We operate this website and the Deephour mobile application. For any privacy question, write to hello@yxtx.tech.
2. This website
yxtx.tech is a static site. We do not require an account, we do not set advertising or analytics cookies, and we do not ask you for personal information. Our hosting provider may record standard technical logs (IP address, user agent, requested page) for security and reliability purposes.
3. What the Deephour app stores, and where
| Data | Where it lives | Sent to us? |
|---|---|---|
| Study topics, reflection notes, questions, answers, retention scores | On your device only | No — except as described in section 4 |
| App settings, focus session durations | On your device | No |
| Subscription status | Managed by Apple / Google | We receive only an entitlement flag, never your payment details |
| Anonymous usage events (e.g. "session completed") | Privacy-preserving analytics | Yes, without identifiers tied to you |
Because your study content stays on device, deleting the app deletes that data. There is no server-side copy to erase.
4. When your text leaves your device
One feature requires a network request: generating recall questions from what you just studied. When you start a recall check, the app sends a minimal payload — the topic name and, if you wrote one, your reflection line — to our server, which forwards it to a third-party language model to produce the questions.
- The request is used to answer that one request and is not written to a database.
- Your text is not used to train any model.
- No account identifier is attached to the request.
- If the request fails, the app falls back to on-device prompts and the session still completes. Your focus session never depends on the network.
You can use Deephour without this feature by declining the recall check; the timer and statistics continue to work fully offline.
5. Third parties
- Cloudflare — hosts this site and runs our API edge functions.
- OpenAI — provides the language model used to generate and grade recall questions. Receives only the minimal text described in section 4.
- RevenueCat — manages subscription entitlements. Receives purchase identifiers, not your study content.
- Apple / Google — process payments for subscriptions. We never receive your card or account credentials.
We do not include advertising SDKs, and we do not share data with data brokers.
6. What we never collect
We do not collect your contacts, photos, precise location, health data, browsing history outside our app, or advertising identifiers. The app does not contain third-party tracking SDKs.
7. Children
Deephour is not directed to children under 13, and we do not knowingly collect personal information from them. If you believe a child has provided us data, contact us and we will delete it.
8. Your choices
- Delete everything — delete the app; local data goes with it.
- Opt out of AI features — skip the recall check; the rest of the app works offline.
- Opt out of analytics — available in Settings.
- Ask us — write to hello@yxtx.tech for any access or deletion request. We respond within 30 days.
9. Data retention
Study content: on your device until you delete it. AI request payloads: transient, not retained. Anonymous analytics: aggregated and retained no longer than 24 months. Subscription records: retained as long as required by tax and accounting rules.
10. Security
Traffic to our services is encrypted in transit (HTTPS/TLS). Study content is protected by your device's own encryption and passcode. No system is perfectly secure, but because the substantive data never leaves your device, the exposure surface is deliberately small.
11. Changes
If we change this policy in a way that affects you, we will update the date at the top and, for material changes, notify you in the app. Continued use after a change means you accept the updated policy.
12. Contact
Beijing Yixing Tianxia Technology Co., Ltd.
北京翊行天下科技有限责任公司 · Beijing, China
hello@yxtx.tech