Privacy Policy
Last updated: April 10, 2026
Kotogoo is developed and operated by Nguyen Quang Trung (individual developer). This policy explains what data we collect, why we collect it, and how we use it when you use our Japanese language learning app and website.
1. Information We Collect
Account Information
When you create an account, we collect:
- Email address
- Display name (chosen by you)
- Authentication data (via Firebase Auth)
- Account creation date and last login
Voice & Audio Data
Kotogoo uses voice in four distinct ways:
- On-device or platform speech-to-text (your voice → text): For regular speaking practice and microphone-based input outside Live Chat, your spoken Japanese may be processed by your platform's speech recognition service, such as Android SpeechRecognizer or Apple's Speech framework on iOS. We do not store raw audio from this flow on our servers.
- Cloud speech-to-text fallback (your voice → text): In some cases, including when on-device speech recognition is unavailable or not working reliably, Kotogoo may send a short audio clip from your microphone to Kotogoo's backend and to OpenAI's speech-to-text API to generate a transcript. This fallback is used only to provide the voice input feature you requested.
- Live voice chat on iOS (Gemini Live): When you start Live Chat on iOS, your microphone audio is streamed in real time from your device to Google Gemini Live so the conversation can happen instantly. Kotogoo does not store raw live audio on its servers.
- Text-to-speech (bot replies → audio): The text of bot replies is sent to third-party AI voice services (see Section 3) to generate spoken audio. The text content is transmitted to and processed by those services.
When cloud speech-to-text fallback is used, Kotogoo may also process the resulting transcript, along with the current lesson or conversation context, to generate the requested AI reply, practice feedback, or audio response.
Story, Practice, and Live Session Data
- Stories and chapters you have accessed
- Story chat content, transcripts, and practice input that you send when requesting AI replies, translations, analysis, summaries, pronunciation feedback, or speech-to-text processing
- Saved custom live topics (
customLiveTopics) if you choose to save them to your account - Saved live session history (
liveSessionHistory), including session metadata and evaluation results such as score, summary, strengths, improvements, and key phrases, when a signed-in live session is completed and saved - Language preferences and app settings
- Daily AI usage (tracked as "points" based on the cost of AI processing). Each account tier has a daily limit that resets at midnight UTC: Guest — 35 points, Free — 75 points, Premium — 1,000 points. This data is stored in your account to enforce fair usage limits.
- App version and device type (for troubleshooting)
2. How We Use Your Information
- To provide and improve the Kotogoo learning experience
- To save your progress and sync it across devices
- To generate AI replies, translations, pronunciation feedback, and post-session summaries
- To save and sync your custom live topics and saved live session history across devices when you are signed in
- To send account verification and security emails
- To enforce usage limits per account type
- To respond to support requests
3. Third-Party Services & International Data Transfers
Firebase (Google)
We use Firebase for authentication, database storage, and app hosting. This includes account records, story progress, usage counters, saved custom live topics, and saved live session history. Your data is stored on Google's servers, which may be located outside your country of residence. See Firebase Privacy Policy.
AI Chat & Voice Services
Kotogoo sends different types of content to different AI providers depending on the feature you use:
- OpenRouter / OpenAI or another configured language-model provider — story chat responses, practice feedback, post-session summary generation, and cloud speech-to-text fallback for supported microphone flows. See OpenAI Privacy Policy.
- Google Gemini Live — real-time live voice chat on iOS, including live audio, transcript/context processing, and model responses. See Google Privacy Policy.
- Google, OpenAI, or an equivalent text-to-speech provider — spoken bot voice generation from reply text.
For story chat and practice features, the content you send is processed to generate the requested response or feedback. For supported speech-to-text fallback flows, a short audio clip may be transmitted through Kotogoo's backend to OpenAI to produce a transcript, and that transcript may then be used to continue the requested conversation flow. For iOS Live Chat, microphone audio is streamed directly from the app to Google Gemini Live in real time, and after a live session ends, the conversation history and practice configuration may be sent through Kotogoo's backend and AI provider stack to generate a session summary.
We do not sell your conversation data. Third-party AI providers may retain certain inputs and outputs for service operations, safety, and abuse prevention under their own policies.
Apple Speech Recognition
For standard microphone-based speech-to-text on iOS outside Gemini Live, your voice audio may be processed by Apple's Speech Recognition service (iOS Speech framework / SFSpeechRecognizer) to transcribe what you said. This is separate from iOS Live Chat with Gemini Live. Audio handled by Apple's speech services is subject to Apple's privacy practices. We do not receive or store raw audio from that standard speech-recognition flow. See Apple Privacy Policy.
OpenAI Speech-to-Text API
When Kotogoo uses cloud speech-to-text fallback, short microphone audio clips and the resulting transcripts may be processed by OpenAI to convert speech into text and support the requested conversation or practice flow. Kotogoo does not use customer audio submitted through the OpenAI API to train OpenAI models by default. OpenAI may retain API data for limited periods for abuse monitoring and service operations under its own policies. See OpenAI API data controls and OpenAI Privacy Policy.
Google Sign-In
If you sign in with Google, Google shares your name and email with us. See Google Privacy Policy.
Sign in with Apple
If you sign in with Apple, Apple shares a verified email address (or a private relay address at your option) and your name with us. See Apple Privacy Policy.
Google AdMob (Rewarded Ads)
Free-tier users may choose to watch a short rewarded advertisement to earn additional tokens. These ads are served by Google AdMob, which may collect device identifiers and usage data for ad delivery and measurement purposes. You can opt out of personalised ads in your device settings (iOS: Settings → Privacy & Security → Apple Advertising; Android: Settings → Google → Ads). See Google Ads Privacy Policy.
Google Play & Apple App Store
When you purchase a Premium subscription, payment is processed by Google Play or Apple App Store. We do not store your payment card details. See their respective privacy policies for details.
By using Kotogoo, you consent to your data being transferred to and processed in countries outside your own, including the United States and Vietnam, in accordance with this Privacy Policy.
4. Advertising
Kotogoo displays opt-in rewarded advertisements via Google AdMob for free-tier users who choose to watch an ad to earn additional tokens. We do not display banner ads, interstitial ads, or any other non-voluntary advertising. We do not share your data with advertising networks for marketing or targeting purposes beyond what AdMob requires to serve and measure the rewarded ad you explicitly requested.
5. Data Retention
We retain data only as long as needed to operate the service, support your account, and provide saved learning features:
- Account information, story progress, settings, and usage counters are retained while your account is active.
- Story chat content, transcripts, and standard practice input are processed when you request an AI reply, transcription, translation, analysis, summary, or text-to-speech output. Some local story chat history may also be cached on your device to restore progress between launches.
- Saved custom live topics (
customLiveTopics) are stored in Firestore until you delete them in-app or delete your account. - Saved live session history (
liveSessionHistory) is stored in Firestore as session metadata and evaluation results, not the full conversation transcript, until you delete an individual saved session in-app or delete your account. - Backend live session accounting records used to reserve and reconcile token usage are retained only as long as needed for service operations and are deleted when your account is deleted.
- Raw live audio is not stored on Kotogoo servers.
- Raw audio clips used for cloud speech-to-text fallback are not stored as saved learning history on Kotogoo servers. Limited temporary processing logs and third-party provider retention may still apply.
- Third-party AI providers may retain certain inputs and outputs according to their own retention policies.
When you delete your account, we permanently delete your profile information, story progress, chat history stored under your account, saved custom live topics, saved live session history, backend live session accounting records, and your Firebase Auth account. Third-party provider logs, including logs related to cloud speech-to-text processing, are governed by those providers' own privacy policies.
6. Your Rights
You have the right to:
- Access the data we hold about you
- Request correction of inaccurate data
- Delete your account and all associated data (available in-app under Profile → Delete Account)
- Delete individual saved live topics and saved live session history entries from the Profile screen
- Export your data — contact us at vn38tr@gmail.com
- EU/EEA users (GDPR): You may object to processing, request data portability, and lodge a complaint with your local data protection authority
- California residents (CCPA): You have the right to know what data we collect, request deletion, and opt out of sale (we do not sell your data)
7. Children's Privacy
Kotogoo is not directed to children under 13. We do not knowingly collect personal information from children under 13. If you believe a child has provided us with personal information, please contact us immediately.
8. Security
We implement industry-standard security measures including encrypted data transmission (HTTPS/TLS), Firebase security rules, and regular security reviews. No method of transmission over the internet is 100% secure, but we strive to protect your data.
9. Changes to This Policy
We may update this Privacy Policy from time to time. We will notify you of significant changes by email or by displaying a notice in the app. Your continued use of Kotogoo after changes constitutes acceptance of the updated policy.