Stacks

Privacy Policy

Effective April 25, 2026

This Privacy Policy describes how Kelp Software ("we", "us") collects, uses, and shares information when you use Stacks (the "App"). By using the App, you agree to this policy.

Information we collect

We aim to collect as little as possible. Specifically:

  • Account information: the email address you use to sign in, an internal user identifier, and an optional display name and friend code you choose.
  • Friend connections: records of which accounts you have added as friends and the friend codes you exchange.
  • Listening sessions: when you join or host a shared listening session, we record the session code, participant list, and playback metadata (current chapter, position, playback speed) needed to keep listeners in sync.
  • Diagnostic information: if the App crashes or encounters an error, we may collect basic diagnostic data such as the device model, operating system version, and a stack trace. This data is not tied to your identity beyond your user identifier.

Information we do not collect

  • We do not run third-party advertising and do not collect data for advertising purposes.
  • We do not collect the content of audiobooks or other files you load into the App. Audiobook files you import are stored on your device. When you transfer a file to a friend, the file moves directly between devices over your local network and is not uploaded to our servers.
  • We do not collect precise location data.

How we use information

  • To create and maintain your account.
  • To provide core functionality (friend lists, shared sessions, casting).
  • To diagnose and fix bugs and to improve reliability.
  • To enforce our Terms of Service and respond to abuse reports.

Service providers

We use the following third-party services to operate the App. Each one has its own privacy policy, and we share only what is necessary for them to provide their service:

  • Supabase (authentication and database hosting) — stores account, friend, and session records described above.
  • Apple and Google — for app distribution, push notifications, and (on Android) Firebase Cloud Messaging delivery.
  • Google Cast — when you cast playback to a Cast-enabled device, the receiver device handles playback over your local network.

Local-network features

Stacks uses your device's local Wi-Fi network to discover nearby devices, transfer audiobook files between friends, and cast audio. These features operate device-to-device over your network. We do not receive copies of files transferred this way.

Data retention and deletion

We retain account data for as long as your account is active. You can request deletion of your account and associated data at any time by emailing dev@kelpsoftware.com from the address associated with your account. We will delete your data within 30 days of receiving a verified request, except where retention is required by law.

Children

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

Security

We use industry-standard transport encryption (HTTPS/TLS) for traffic between the App and our servers. No system is perfectly secure, but we take reasonable steps to protect your information.

Changes to this policy

We may update this Privacy Policy from time to time. We will post the revised policy at this URL with an updated effective date. Material changes will be communicated in-app or by email where appropriate.

Contact

Questions or requests? Email dev@kelpsoftware.com.