温故Wengu

Wengu Privacy Policy

Effective: September 4, 2026

Wengu (温故) is an HSK Chinese vocabulary study app made by an independent developer. This policy covers the app and the wengu.co website: what we collect, why, and what we never do. The short version: we collect the minimum needed to sign you in, sync your study progress across your devices, and unlock what you have paid for. No ads, no trackers, no selling of data.

1. What the app collects

Account. Your email address, used to create and sign in to your account — either with a one-time code, or through Sign in with Apple. If you use Sign in with Apple and choose Hide My Email, we receive only Apple's private relay address, never your real one.

Study data. Your review history, spaced-repetition scheduling state, study sessions, streaks, chosen HSK level and daily goal, and app settings that sync. This is the data that lets your progress follow you across devices.

Purchases. If you subscribe to Wengu Pro, Apple handles the payment; we never see your card or billing details. From Apple we receive the transaction and subscription identifiers, the product you bought, and its status and renewal dates. We store these so the app knows what to unlock and can restore your purchase on a new device.

Card reports. If you flag a card as incorrect, we receive the flag and the card it refers to so we can fix the content.

Deletion feedback. If you delete your account, you may optionally leave feedback. It is stored anonymously and is not linked to you.

That's the full list for the app. We do not collect your name, contacts, location, photos, device identifiers, or anything else.

2. What stays on your device

Study reminders are scheduled on your phone by the app itself. There is no push server, and nothing about your reminders leaves the device. Home-screen widgets read a copy of your progress that the app keeps on the device. Your vocabulary, audio and review history are cached locally so Wengu works offline.

3. The website

wengu.co sets no cookies and loads no advertising or tracking scripts. To count visits and measure page speed we use Vercel Web Analytics and Speed Insights, which are cookieless and record no personal data: a visit is attributed to a hashed identifier that is discarded within a day, and no IP address is stored. If you request a beta invitation or join the Android waitlist, we store the name and email you enter, which list you joined, and the language the page was in. We use them to send you the message you asked for, and any early-supporter thank-you we have promised. Write to support@wengu.co to be removed from either list at any time.

4. Where your data lives

Wengu is offline-first: your study data lives on your device and works without a connection. When you're online, it syncs to our backend, hosted by Supabase (managed PostgreSQL), encrypted in transit. Audio and content are delivered through Cloudflare's content delivery network, which transiently processes your IP address to serve files — as any web request does. The emails we send — sign-in codes and the waitlist messages above — go through Resend, an email delivery provider acting on our behalf. These providers process data on our behalf and have no right to use it for their own purposes.

If you use Game Center achievements, those are reported to Apple's Game Center and governed by Apple's privacy policy. We do not store your Game Center identity on our servers.

5. What we don't do

  • No third-party analytics or advertising SDKs in the app.
  • No tracking across other companies' apps or websites.
  • No selling or sharing of your data for marketing.
  • No reading of your data beyond what operating the service requires.

6. Your controls

  • Sign out at any time; your local data stays on your device.
  • Delete your account directly in the app: open Profile, then Settings, and use Delete Account at the bottom of the page. This permanently removes your account and all synced study data from our servers. No email required, no waiting period. Records of past purchases are kept for accounting and refund handling, with the link to your account removed.
  • Your rights. Wherever you live, you can ask us to access, correct, export, or delete your data: support@wengu.co.

7. Children

Wengu is not directed at children under 13, and we do not knowingly collect personal information from them. If you believe a child has created an account, contact us and we will delete it.

8. Changes

If this policy changes, the current version will always be at this address, with its effective date. Material changes will be noted in the app.

9. Contact

support@wengu.co — we read everything.