Privacy Policy
Overview
Black Koi Wallet is a free, open-source Android application designed to teach Bitcoin self-custody through hands-on practice. We are committed to your privacy. This policy explains clearly and completely what data is collected, why, and how it is handled.
What the app collects
The Black Koi Wallet app itself collects no personal data. There are no user accounts, no registration, no analytics SDK, no crash reporting service, and no advertising framework of any kind embedded in the app.
Faucet service
To support the learning experience, the app connects to a faucet service hosted at faucet.blackkoi.org. When you request practice bitcoin, the following information is transmitted to and processed by the faucet server:
| Data | Purpose | Retained? |
|---|---|---|
| Bitcoin wallet address | To send practice sats to your wallet | Stored to prevent duplicate requests |
| Random device identifier (UUID) | To enforce per-device rate limiting | Stored to prevent abuse |
| IP address | Rate limiting during request processing | Not stored by the app or faucet service; may be temporarily retained in web server access logs for operational and security purposes, as is standard practice for any web service |
The wallet address and device UUID are not personally identifiable information. They cannot be used to identify you as an individual. They are stored solely to ensure fair access to the faucet and are never sold, shared, or used for any other purpose.
What we do not collect
- No names, email addresses, or contact information
- No location data
- No device identifiers beyond the anonymous UUID described above
- No usage analytics or behavioral tracking
- No financial information (testnet coins have no monetary value)
Third-party services
Google Play — If you installed Black Koi Wallet through Google Play, Google collects certain data as part of its platform (installs, crash reports, ratings). This is governed by Google's Privacy Policy and is outside our control.
No other third-party services are used.
Open source
Black Koi Wallet is fully open-source under the Apache 2.0 license. You can inspect the complete source code, including all network calls, at:
github.com/Kokufuu/black-koi-wallet
Children
Black Koi Wallet is not directed at children under the age of 13 and does not knowingly collect any information from children.
Changes to this policy
If this policy changes materially, we will update the date at the top of this page. Continued use of the app after changes constitutes acceptance of the updated policy.
Contact
Questions about this privacy policy can be sent to:
hello@blackkoi.org