Privacy Policy

1. What we do not collect

CastFi does not collect any of the following.

• Personal identifiers such as name, phone number or date of birth — the app requires no account. An email address is collected only if you create an account (see section 8).
• Contacts, call logs or messages.
• Location of any kind (GPS, precise or approximate).
• Microphone, camera, photos or videos.
• Advertising identifiers. The CastFi Android app currently contains no advertising.
• Any record linking you personally to what you listened to and when.
• Persistent hardware identifiers (IMEI, advertising ID, MAC address and the like).

2. Information processed only on your device

The following stays on the device and is never transmitted.

• Music files — CastFi reads audio only from folders you select yourself. It does not scan the whole device automatically, and the files themselves are never uploaded to any server.
• Library index — title, artist, album, duration and file location read from your files, stored in a database inside the app.
• Settings — sound correction values, playlists, display preferences and the list of devices you have connected.

Uninstalling the app, or clearing its data in system settings, removes all of it.

3. Permissions the app requests

These are the permissions CastFi uses and why. Each is requested when it is actually needed; declining one disables only the related feature rather than locking the app.

Notification access (optional)

Android requires notification access before an app can show and control what another music app is playing. CastFi uses it only to read the active media session (track title, artist, playback state) and to send playback commands. Notification content is neither stored nor transmitted. Without this permission, CastFi's own playback and every other feature continue to work normally.

Sharing this phone's music (optional)

When you turn on Settings > Share this phone's music, other CastFi devices on the same Wi-Fi can see this phone's music list (track details and album art), stream the files, or have them play on this phone. It is off by default, accepts connections only from your private home network, and never reveals file paths. Everything goes directly between your devices — not through CastFi's servers or the internet. Turning it off blocks access immediately.

4. Information sent outside the device

4-1. Lyrics and video lookup

When you use lyrics or music video features, the track title and artist name are sent to public third-party services to perform the lookup. Nothing identifying you is sent with them, and no request is made if you do not use those features.

4-2. Anonymous usage statistics (optional, can be turned off)

To improve the app we collect anonymous statistics. This can be switched off in settings, and only the following is transmitted.

• The event name (for example, app opened) and the time it occurred.
• A randomly generated installation identifier — an arbitrary value that identifies neither you nor your device. It disappears when the app is uninstalled or its data cleared, and a different value is generated next time.
• A session identifier that is regenerated after 30 minutes of inactivity.
• Operating system name and version, app version, and language setting.
• When an exclusive playback session through a USB audio device (USB DAC) ends in the Android app, a summary of that session, used to improve playback stability across USB audio devices and phone models:
  • The playback path (PCM, native DSD or DoP), the outcome (normal, recovered, stalled, rejected or error) and a short reason code.
  • The playback duration band (under 5 seconds, 5–60 seconds, 60–600 seconds or over 600 seconds) and the number of automatic recoveries.
  • The vendor and product numbers of the connected USB audio device (USB VID/PID, for example 2972:0047).
  • The phone model name (for example SM-S948N) and chipset name (for example SM8850).
  These values describe product models and are the same for everyone with the same model, so they do not identify you. The device's product name string, serial number, track information and file paths are not sent, and the number of these summaries sent per installation per day is capped.

This data goes to a receiving server operated by CastFi and is not linked to any account or to messages you send us. The server records a two-letter country code (for example KR) determined at the point of connection, or XX when it cannot be determined. IP address, city, region, coordinates and carrier details are not stored. The IP is used only to determine the country and is never retained in any form.

4-3. Automatic crash reports (optional, can be turned off)

If the app terminates unexpectedly, the error type, a summary of where it occurred, and the app and OS versions are sent so the fault can be found. It uses the same anonymous identifiers as 4-2 and contains no personal information and no content from your music files. It can be turned off separately from usage statistics.

4-4. Messages and reports you send yourself

When you report a problem or send feedback from inside the app, what you wrote is transmitted along with environment details needed to investigate (app version, OS version, device model). This happens only when you press send. The data is stored on infrastructure provided by Supabase Inc. and is used solely to answer you and to fix the defect.

5. Connections between your devices

Music and control signals exchanged with a PC, network player or NAS on the same Wi-Fi travel directly between the devices. They do not pass through a CastFi server and their content is not stored anywhere else.

If you use the remote feature to reach your own PC from outside your home, only the connection details the two devices need to find each other pass through an intermediary; the music itself is transferred directly between your two devices. The feature works only for devices you have registered yourself.

When you add a NAS (network storage) in the Android app, the sign-in details you enter are kept only if you choose to save them, encrypted in that device’s secure storage, and are never sent to a CastFi server or anywhere else. The connection to the NAS is made directly between the device and the NAS on the same network (or a VPN you set up yourself).

Cloud storage (OneDrive · optional)

If you connect a OneDrive account to CastFi in the Android app, CastFi uses the audio files under the music folders you add, read-only. CastFi has no feature that modifies, deletes or shares your cloud files.

• Purpose — building the song list for the folders you add (reading tags such as title and artist, and album art), keeping it in sync with later additions, renames, moves and deletions, playback and seeking, and saving offline copies of songs you choose. CastFi does not use this data for anything else.
• Direct transfer — file lists and music data travel directly between Microsoft’s servers and your device. They do not pass through, and are not stored on, CastFi servers.
• What stays on the device — the list of files under your added folders (file ID, name, size, version), music tags and album art, and any offline copies you download. All of it stays on this device only.
• Sign-in — OneDrive sign-in details are kept encrypted in this device’s secure storage and are never sent to a CastFi server.
• Scope of access — Microsoft’s ‘Open your OneDrive files’ permission is used only for the folders you add. CastFi only reads music files under the folders you add.
• What we never do — data received from your cloud storage is not used for advertising, analytics, or training AI or machine-learning models, and is never sold or transferred to third parties. No person reads it, except where you include it in a message or report you send us, for security purposes, or to comply with the law.
• Disconnecting — removing the account in the app’s cloud storage screen deletes that account’s folders and file list from the device. Offline copies you downloaded and the original files in your cloud storage stay as they are. You can also revoke access at any time in your Microsoft account’s app permissions.

6. External music services

When CastFi for Windows is used with services such as Spotify, YouTube Music or Apple Music, you sign in to each service directly and that service's own privacy policy applies. CastFi does not send your sign-in details to any server of its own.

7. Sharing with third parties

CastFi does not sell the information it collects and does not share it with third parties for advertising. The following providers supply infrastructure needed to run the service.

• Supabase Inc. — storage and handling of messages and reports you send yourself.
• Lyrics and video providers — lookups by track title and artist name, when you use those features.

8. Retention and deletion

• Information stored on the device (library index, settings) disappears the moment you uninstall the app or clear its data.
• Anonymous statistics and crash records are retained for aggregate analysis. Because they cannot identify an individual, they cannot be deleted on request; turning the setting off stops any further transmission.
• Messages and reports you sent are deleted once they are no longer needed to answer you. To have them removed sooner, write to support@castplan.net.

Account information

An account is optional. When you create one we store your email address and sign-in credentials (a password only in an irreversible form; with Google sign-in, the email and account identifier Google provides) together with sign-up and sign-in timestamps. This information is used only to keep you signed in, to verify purchased plans and to answer your requests.

Account information is stored and processed on servers operated by Supabase Inc. (United States). This is a transfer of personal data abroad: the items transferred are the account information above, the purpose is authentication and plan management, and it is retained until deletion as described below.

Deleting your account

You can delete your account inside the app (Settings › Account › Delete account) or, without reinstalling, at castfi.castplan.net/delete-account. Deletion immediately removes the account (sign-in identity), email address, entitlement records and trial record, and cannot be undone.

What is kept after deletion. So that purchases can be restored, a minimal payment ledger (such as purchase verification tokens) and the pseudonymous billing identifier tied to them (a one-way value derived from the sign-in identity that does not identify you on its own) are retained after the account is deleted. Sign up again with the same address and purchased plans are restored. Payment records are kept for the period required by e-commerce law.

If you never created an account there is nothing to delete, and uninstalling leaves nothing behind on the device.

9. Children

CastFi is not directed at children and does not knowingly collect personal information from them. If you believe a child's information has been sent to us, contact us at the address above and we will verify and delete it.

10. Changes to this policy

If this policy changes, the revision and its date are published on this page. Significant changes are also announced inside the app.

11. Contact

Questions about privacy: support@castplan.net