对话duìhuà · conversation practice

Privacy Policy

Last updated: 24 August 2026

对话 (Duìhuà) is a Mandarin conversation-practice app published by 404AI. This policy explains what data the app handles and why. We collect as little as possible: we do not sell your data, we do not show advertising, and the app contains no third-party advertising or tracking SDKs.

What we store on our servers

When you sign in and subscribe, we store the minimum needed to run your account and entitlement, on Cloudflare infrastructure:

A unique account identifier provided by Sign in with Apple (we do not require or rely on your name or email).
Your subscription status — the Apple transaction identifier, plan state, and renewal/expiry date — which we verify with Apple's App Store Server API.
A count of free practice turns used, to apply the free tier.
Your learning data, for cross-device sync: the text of your practice conversations, saved vocabulary, pronunciation progress, and achievements, stored against your account identifier — so your history survives a lost or replaced device and follows you when you sign in on another one. Because conversations are free-form, this content can include whatever you choose to talk about; it is stored to provide the service to you, is not used for advertising or profiling, and is not sold or shared beyond the processing described below.
A conversation you choose to share: if you tick "share this conversation" when rating one, that transcript is stored so we can review it to improve the app.

We do not store your voice recordings anywhere — audio is processed transiently for transcription and scoring, then discarded. Server-side data is encrypted at rest and in transit, and your synced learning data is accessible only through your own signed-in session.

What stays on your device

The app is local-first: your conversation history, vocabulary, progress, and settings are stored on your device, and the app works from that local copy. Signed-in devices also keep the learning data (not your settings) mirrored to our servers, as described above. Deleting the app removes the local copy; the server copy remains until you ask us to delete it (below).

Voice and conversation processing

To provide the core features, content is sent to third-party processors purely to perform the task you requested, and is governed by their respective policies:

Your speech (audio): sent to Google (Gemini) for transcription and spoken-language coaching, and to iFlytek for pronunciation scoring and text-to-speech.
Your conversation text: sent to the language-model provider selected in your settings — which may be DeepSeek, Google (Gemini), Anthropic, or Alibaba Cloud (Qwen) — to generate replies and feedback.

This audio and text is processed to deliver the feature; we do not use it to build advertising or marketing profiles.

Payments

Subscriptions are billed by Apple through your Apple ID. We never receive or store your payment card details. You can view or cancel your subscription at any time in your Apple ID settings (Settings → your name → Subscriptions), or from the "manage or cancel subscription" link in the app.

Data retention and deletion

We keep your account, subscription, and synced learning data for as long as your account exists. You can delete your account and everything we hold about you — your Apple account identifier, subscription record, synced learning data, and any conversations you shared — directly in the app: Settings → account → delete account & data. This also erases the app's data on your device. Deleting your account does not cancel an active subscription — manage that in your Apple ID settings. You can also request deletion by contacting us at the address below.

Children

对话 is not directed at children and is not intended for use by children under 13.

Changes

We may update this policy; material changes will be reflected by the "last updated" date above.

Contact

Questions or requests: sasha@404.com.au.