Libellus Potionis

Libellus Potionis is a privacy-first, free, open-source and ad-free alcohol consumption tracker. It helps you monitor, pace and manage your drinking entirely offline. It needs no invasive permissions — no camera, microphone or location — and works completely without network access.

KEY FEATURES

• Intelligent logging: predefine your own beverages or pick from internationally common presets. Log drinks instantly or retroactively with precise timestamp corrections.
• Concurrent limit tracking: set three simultaneous boundaries — a daily limit (grams of pure alcohol), a rolling 7-day weekly limit (grams), and a maximum number of drinking days per week. Visual progress bars keep you informed in real time.
• Blood Alcohol Concentration (BAC) estimate: enter your body weight to get a live approximation based on the established Widmark formula.
• Counseling reports: generate a clear, well-organized two-page PDF report designed for consultations and counseling appointments, summarizing your habits statistically.
• Data portability: export your full dataset as a standard CSV file for external processing (e.g. in LibreOffice Calc), or create secure JSON backups to move data between devices.
• Granular adjustments: customize your "day start" time so late-night drinks count toward the correct evening, and set custom evaluation start dates for clean restarts.

A comprehensive User's Guide is available inside the app.

PRIVACY & SECURITY

Libellus Potionis is built around absolute data sovereignty and strict data minimization. It runs under a minimal permission profile that completely excludes network access, so your personal data never leaves the device. 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. This offline-first approach eliminates tracking, cloud synchronization and external data leaks.

COMPATIBILITY

The app runs on Android 11 (API 30) and newer. A fully independent in-app language selector works across all supported versions, regardless of the system-level per-app language picker.

OPEN SOURCE

Libellus Potionis is free software released under the GNU General Public License v3 (or later). The source code is documented to a textbook standard and is available at the canonical repository: https://codeberg.org/godisch/potillus/

Fixed: importing a backup with "Replace" now really replaces the drink list — the built-in preset drinks are no longer kept alongside the imported ones. Fixed: the Statistics and Calendar cards now have the same background as the rest of the app. The language list now offers "(System)", so a fixed language can be switched back to following the device language. And the overflow menu's About screen shows the version, the GPL notice and the licenses of the app's components.