Libellus Potionis

Libellus Potionis is a privacy-first, open-source, free and ad-free alcohol consumption tracker designed to help users monitor, pace, and manage their drinking habits entirely offline. It requires no invasive device permissions—no camera, microphone, or location access—and operates completely without network connectivity.

KEY FEATURES

• Logging: Predefine your own beverages or pick from internationally common presets. Log drinks instantly or retroactively with timestamp corrections.
• Concurrent limits: Set three boundaries at once — a daily limit (grams of pure alcohol), a rolling 7-day weekly limit (grams), and a maximum number of drinking days per week. Each has its own progress bar.
• Blood alcohol concentration (BAC): Enter your body weight to get a live estimate from the Widmark formula.
• Counseling reports: Generate a two-page PDF report of your consumption for consultations and counseling appointments.
• Data portability: Export your dataset as a CSV file for external processing (e.g. in LibreOffice Calc), or create JSON backups to move data between devices.
• Adjustments: Set your own “day start” time, so that late-night drinks count toward the preceding evening, and an evaluation start date for a clean restart, e.g. on New Year’s Eve.

A User’s Guide is available inside the app.

PRIVACY & SECURITY

The app stores only what you enter. It holds no network permission, so it is incapable of network access and your data cannot leave the device by itself. Your data stays in the app’s private storage, protected at rest by Android’s device storage encryption and the app sandbox. An optional biometric fingerprint lock guards against unauthorized physical access. There is no tracking, no analytics and no cloud synchronization.

COMPATIBILITY

The app runs on Android 11 (API 30) and newer and is also available for iOS 17 and newer.

OPEN SOURCE

Libellus Potionis is free software released under the GNU General Public License v3 (or later). The source code is available at the project homepage.