Legal

Privacy Policy

Effective date: April 1, 2025 · Last updated: April 24, 2026

1. Who We Are

Card Doppler (“we,” “us,” or “our”) operates the website carddoppler.com and related services. We provide market intelligence tools for trading-card collectors, including price research, portfolio tracking, and SMS-based price alerts.

Questions? Email us at carddoppler@gmail.com.

2. Information We Collect

Account information: email address and password (hashed) when you register.
Collection data: card names, purchase prices, grades, images, and notes you enter into your collection.
Phone number: provided voluntarily when you create an SMS price alert. Used exclusively to deliver the alert messages you configure.
Payment information: processed securely by Stripe. We do not store full card numbers or CVVs.
Usage data: pages visited, search queries, and feature interactions, collected through standard server logs and analytics.

3. How We Use Your Information

To operate and improve the Card Doppler platform.
To send you SMS price alerts that you explicitly opt in to (see Section 5).
To process subscription payments via Stripe.
To respond to support inquiries.
To detect and prevent fraud or abuse.

We do not sell your personal information to third parties and do not use your data for advertising purposes.

4. Data Sharing

We share data only with:

Supabase — our database and authentication provider.
Stripe — payment processing.
Twilio — delivery of SMS alert messages to your phone number.
eBay — we query the eBay Finding API to retrieve publicly available sold and active listings on your behalf.

All third-party providers are required to handle your data in accordance with applicable privacy laws.

5. SMS Alerts — Opt-In & Opt-Out

SMS Program Disclosure

Card Doppler sends transactional SMS messages to notify you when a card you are tracking reaches a price threshold you have configured. These are not marketing messages.

Opt-in: You provide your phone number and check the consent box in the Alert setup form. Alerts are triggered only by conditions you set.
Frequency: Message frequency depends on the number of alerts you configure and market activity. Typically 0–10 messages per day.
Opt-out: Reply STOP to any message at any time to unsubscribe. You can also delete your alerts from the Alerts page.
Help: Reply HELP for support, or email carddoppler@gmail.com.
Carriers: Message and data rates may apply. Supported carriers include all major US carriers.

6. Data Retention

We retain your account and collection data for as long as your account is active. You may delete your account and all associated data at any time by contacting us at carddoppler@gmail.com. Phone numbers are retained only while you have active alerts and deleted when alerts are removed or the account is closed.

7. Cookies & Analytics

We use cookies and similar technologies to maintain your login session and understand how the service is used. We do not use third-party advertising cookies. You may disable cookies in your browser settings, though some features will not function without them.

8. Security

We use industry-standard security practices including HTTPS, encrypted storage, and hashed passwords. No method of transmission or storage is 100% secure, and we cannot guarantee absolute security.

9. Children's Privacy

Card Doppler is not directed at children under 13. We do not knowingly collect personal information from children. If you believe a child has provided us with personal information, please contact us and we will delete it.

10. Changes to This Policy

We may update this policy periodically. We will notify registered users by email of material changes. Continued use of the service after changes take effect constitutes acceptance of the revised policy.

11. Contact

Card Doppler
carddoppler@gmail.com