Privacy Policy

Hibiki Voice ("we", "us", "our") operates the Hibiki Voice mobile application and the website at hibikivoice.com (together, the "Service"). This Privacy Policy explains what information we collect, how we use it, and the choices you have.

The Service helps people who are learning Japanese improve their pronunciation by practicing speaking a word or sentence on screen and receiving instant, mora-level feedback.

Account information: when you create an account we collect your email address. Authentication is handled by better-auth, which hashes credentials and issues an HTTP-only session cookie.

Audio recordings: when you use the Speak button, we capture a short voice recording of your pronunciation and send it to our servers for assessment. The recording is forwarded to our assessment providers (see "Third-party services") and is not retained long-term as raw audio.

Assessment results: we persist a normalized pronunciation snapshot (reference text, recognized text, overall and per-mora scores, and the calculated tier) so you can review your progress.

Device identifiers: when you practice without signing in (for example during onboarding), we generate a stable anonymous device id stored in expo-secure-store on native or localStorage on web. This is used only to enforce the anonymous trial quota.

Usage counters: we store a monthly pronunciation-assessment count (apiCallsUsed) and a reset date (quotaResetDate) on your user document so we can enforce per-tier monthly quotas.

Progress data: we store lesson and practice-run progress, including completed words, attempts, and the lowest tier reached in each practice run.

Subscription state: when you subscribe, Apple App Store / StoreKit provides a transaction id that we verify server-side and use to set your account tier ("paid-0").

To provide pronunciation assessment and mora-level feedback.

To track lesson progress and practice runs so you can resume where you left off.

To enforce monthly pronunciation-assessment quotas per tier and the anonymous per-device trial quota.

To manage your subscription tier and unlock paid lessons.

To generate native-speaker reference audio via Google Cloud Text-to-Speech from the reference text of a lesson page.

To maintain the security and integrity of the Service.

Speechsuper: receives your audio recording and the kanji reference text in order to compute pronunciation, fluency, completeness, rhythm, and pitch-accent scores. Speechsuper processing is governed by its own privacy policy.

OpenAI: receives your audio recording concurrently with Speechsuper to produce a transcription used for mora alignment and tier calculation.

Google Cloud Text-to-Speech: receives the reference text (not your recording) to synthesize the native-speaker model audio you can play back.

Apple App Store / StoreKit: handles subscription billing and transaction verification. We receive the transaction id and verify it via the Apple App Store Server API.

MongoDB: our database provider stores account, progress, quota, and subscription documents.

We retain your account and progress data for the lifetime of your account.

Raw audio recordings are processed for assessment and are not stored long-term; only the normalized pronunciation snapshot (scores and mora analysis) is persisted.

Anonymous device quota records are retained to prevent quota evasion across resets.

Sessions are managed by better-auth with HTTP-only cookies. Apple subscription transactions are verified server-side using signed JWS and the App Store Server API. No measure is perfect, but we apply industry-standard safeguards.

You may request access to, correction of, or deletion of your personal data by contacting luca@hibikivoice.com. We will respond in accordance with applicable law.

You can submit a data-deletion request directly at hibikivoice.com/delete-my-data.

The Service is not directed to children under 13, and we do not knowingly collect personal information from children under 13.

We may update this Privacy Policy from time to time. Material changes will be posted here with an updated "Last updated" date.

Questions about this Privacy Policy can be sent to luca@hibikivoice.com.