Privacy Policy
Last updated: 2026-04-17
Short version. Serum runs entirely on your device. We have no server, no account system, no analytics, and no telemetry. Your regimen and dose log never leave your phone unless you explicitly export them. We cannot see what you take. No one at Leyline Labs LLC can.
What data Serum stores
When you use Serum, the app stores the following on your device:
- Your regimen: compounds you track, dosages, frequencies, and schedules.
- Your dose log: the timestamp and amount of every dose you record.
- Custom compounds and bundles you create.
- App settings: theme, units, reminder times, Pro entitlement state.
- A purchase receipt from the platform store (Google Play or Apple), held by the platform and queried locally to determine whether Pro is unlocked.
All of the above is saved to the app's private sandbox via the operating system's standard storage APIs. It is not accessible to other apps.
What Serum does not do
- No user accounts. There is no sign-up, no login, no username.
- No cloud sync. There is no Serum server. Your data is not backed up to any service operated by us.
- No analytics. We do not collect usage metrics, crash reports, device identifiers, or behavioral data.
- No third-party SDKs for tracking. Serum does not embed Firebase Analytics, Mixpanel, Amplitude, Adjust, AppsFlyer, Facebook SDK, or similar.
- No ads. Serum is free (with an optional one-time Pro purchase) and shows zero advertisements.
Network access
Serum connects to the internet only for the following explicit operations:
- In-app purchase. To verify Pro entitlement, the app talks to Google Play Billing (on Android) or the App Store (on iOS). These are operated by Google and Apple under their respective privacy policies.
- Study links. If you tap a citation link on a compound's detail page, your browser opens the linked DOI or PubMed URL. That destination sees a standard browser request; Serum itself sends nothing.
All other app functionality, including the PK math, dose logging, the charts, interaction warnings, and the medical-grade PDF export, runs offline. You can use Serum in airplane mode indefinitely.
Optional integrations
Serum supports optional integration with your phone's health data store. When you enable this in settings:
- Health Connect (Android) / Apple Health (iOS). Serum can write dose records to your phone's health data store and read them back for history recovery. This is a local, on-device integration. Data goes into the platform's health database on your phone, which is controlled by you through the platform's permission system.
- Reminders. Serum schedules local notifications on your device. These are handled entirely by Android / iOS and never touch our infrastructure (because there is none).
- Export. You can export your regimen as a PDF or CSV, and your full data as a JSON backup. You decide where these files go. Serum does not upload them anywhere.
In-app purchases
Serum Pro is a one-time purchase processed by Google Play Billing or the Apple App Store. The payment itself and any billing records are held by Google or Apple under their own privacy policies. Serum receives only a receipt token that confirms whether the purchase has been made. We do not receive your payment details, card number, or name.
Data you share by choice
If you choose to use the export feature to share a PDF, CSV, or JSON with a clinician or a friend, that file contains your regimen and dose log. Once the file leaves your device, its handling is up to you and the recipient. We have no involvement.
Data retention and deletion
Because Serum stores nothing on our servers, there is nothing for us to retain or delete. On your device:
- Your data persists until you uninstall the app or tap Reset all data in the Settings screen, both of which delete everything.
- Free tier users have dose history older than 90 days automatically pruned. Pro users keep unlimited history.
- Health Connect / Apple Health records you wrote through Serum remain in the platform health store under the platform's retention rules; you can delete them directly there.
Children's privacy
Serum is not directed at children under 13. We do not knowingly collect data from children (or from anyone, for that matter). If you believe a minor has installed Serum, uninstalling the app removes all data.
International use
Serum is available globally. Because we operate no servers and collect no data, there is no cross-border data transfer to describe. All data stays on your device, subject to the laws of whatever jurisdiction your device is physically in.
Changes to this policy
If we add functionality that materially changes how data is handled (for example, if we ever added an optional cloud backup), we will update this page and reflect the change in the app before enabling the feature. The "Last updated" date at the top of this document reflects the most recent material revision.
Contact
Questions, concerns, or privacy requests: contact@serumlog.com.
Serum is developed by Leyline Labs LLC.