Privacy Policy

We collect the following categories of information:

• Account information. When you sign in we store your email address. If you choose to sign in with Google or Apple, that provider shares a basic profile with us (your email address, and where available your name and profile picture) so we can create your account. We use email-based sign-in links and one-time codes — we never receive or store a password.
• Profile and preferences. An optional nickname and profile photo you choose to upload, plus settings such as your theme (light/dark) and time zone.
• Learning data. The data that powers your personalized review schedule: which words you have studied, how you graded your recall, your per-word memory state, and your estimated ability level. This is the core of how the app works.
• Diagnostic and usage data. To keep the app reliable we record lightweight first-party events tied to your account — for example session start/end, level changes, performance timings, and error reports. You can lower the sampling rate for these events in your settings; error reports are kept on so we can fix crashes. This telemetry stays in our own database and is not shared with any third-party analytics service.
• Cookies and local storage. We use a session cookie to keep you signed in and a small preference cookie to remember your theme. We do not use advertising or cross-site tracking cookies.

• Provide your account and keep you signed in across devices.
• Personalize your learning — schedule reviews, estimate your ability, and choose which words to show you next.
• Maintain, debug, secure, and improve the app.
• Respond to your support requests and communicate about your account.

We do not use your information for advertising, profiling for third parties, or automated decisions with legal effects.

We do not sell your personal information and we do not share it with advertisers. We rely on a small number of trusted service providers (data processors) who handle data only on our behalf and under contract:

• Supabase — authentication, database, and file storage (your account, learning data, and uploaded profile photo).
• Vercel — application hosting and delivery; processes standard request data such as IP address in server logs.
• Cloudflare — delivery of audio and static assets. These requests do not include your account data.
• Google and Apple — only if you choose to sign in with one of those providers, and only to authenticate you.

We may also disclose information if required by law, or to protect the rights, safety, and security of our users and our service.

We keep your account and learning data for as long as your account is active. If you delete your account, we delete your personal data and learning history, except where we are required to retain limited records to comply with legal obligations. Aggregated or de-identified data that can no longer be linked to you may be retained.

You can:

• Access and update your profile and preferences in the app.
• Adjust the diagnostic-telemetry sampling rate in your settings.
• Request a copy of your data, or request that we correct or delete it.
• Delete your account, which removes your personal data and learning history.

To exercise any of these rights, email contact@tongtong.app. Depending on where you live, you may have additional rights under laws such as the GDPR or CCPA; we honor those requests for all users.

Connections to TongTong are encrypted in transit (HTTPS). Access to your data is restricted by per-user database security rules so that you can only read and write your own records. No method of transmission or storage is perfectly secure, but we work to protect your information using industry-standard safeguards.

TongTong is rated 4+ and is suitable for general audiences, but it is not directed to children under 13 (or the equivalent minimum age in your country), and we do not knowingly collect personal information from them. If you believe a child has provided us with personal information, contact contact@tongtong.app and we will delete it.

We operate from, and use service providers located in, the United States and other countries. If you access TongTong from outside these regions, your information may be transferred to, stored, and processed there. We take steps to ensure your data remains protected in accordance with this policy.

We may update this policy from time to time. When we make material changes we will revise the “Last updated” date above and, where appropriate, notify you in the app. Your continued use of TongTong after an update means you accept the revised policy.

TongTong’s grammar reference content is adapted from the Chinese Grammar Wiki by AllSet Learning, used under the Creative Commons Attribution-ShareAlike 3.0 (CC BY-SA 3.0) license. Descriptions, structure notes, and example sentences have been edited and supplemented for use in this app.

Questions about this policy or your data? Email us at contact@tongtong.app. We read every message.