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Privacy Policy

Last updated: October 29, 2026

1. Introduction

astro.how ("we", "our", or "us") operates the astro.how website and services. This Privacy Policy explains how we collect, use, disclose, and safeguard your information when you use our service.

2. Information We Collect

Account Information

  • Email address (used for authentication via OTP or Google OAuth)
  • Display name and profile information you choose to provide

Birth Chart Data

  • Date, time, and place of birth you enter for chart calculations
  • Charts are computed client-side in your browser; only saved charts are stored on our servers

Usage Data

  • Practice session history, scores, and XP
  • AI chat messages exchanged during practice sessions
  • Social interactions (comments, likes, shared charts)

Technical Data

  • IP address and browser user-agent (for security and rate limiting)
  • Session cookies (for authentication)

3. How We Use Your Information

  • To provide and maintain the service, including AI-powered practice features
  • To authenticate your identity and manage your account
  • To process payments and unlock the courses or credits you buy
  • To send transactional emails (OTP codes, account notifications)
  • To display leaderboards, social feeds, and community features
  • To improve and optimize the service

4. Data Sharing

We do not sell your personal information. We share data only with:

  • AI providers: Chat messages are sent to a third-party AI model provider to generate practice responses. This provider may process data outside Japan.
  • Payment processors: Stripe processes card and other payments; payments in Chinese yuan may also be processed by Alipay, and LINE Pay payments by LINE Pay. They collect your payment details directly, and we do not store your card number or other payment details. For payments in US dollars, New Taiwan dollars or Hong Kong dollars, Stripe is the merchant of record and handles your billing information under its own privacy policy.
  • Email services: Resend delivers transactional emails on our behalf.
  • Infrastructure providers: Cloudflare provides CDN and DDoS protection.

5. Data Storage and Security

Your data is stored on servers located in Osaka, Japan. We use encrypted connections (HTTPS), session-based authentication, and rate limiting to protect your data. Birth chart computations are performed entirely in your browser and are not transmitted to our servers unless you explicitly save a chart.

6. Cookies

We use only essential cookies for authentication (session cookies). We do not use tracking cookies or third-party analytics cookies.

7. Your Rights

You may:

  • Access, update, or delete your account information
  • Delete your saved charts and practice history
  • Request a copy of your data
  • Request account deletion by contacting us

8. Children's Privacy

Our service is not directed to children under 13. We do not knowingly collect information from children under 13. If you believe a child has provided us with personal data, please contact us.

9. Changes to This Policy

We may update this Privacy Policy from time to time. We will notify you of material changes by posting the new policy on this page with an updated revision date.

10. Contact

If you have questions about this Privacy Policy, please contact us at info@astro.how.