offline-currency-converter

Offline Currency Converter is an Android app that provides currency conversion without requiring an account or ongoing network access. It downloads exchange rates from the Frankfurter API (European Central Bank data) and stores them locally using Room, so all conversions are performed on-device after the initial sync. Users can configure sync intervals from 6 hours to weekly or manual-only, with background updates handled by WorkManager. The app supports over 160 currencies and includes a favorites system for quick access, plus a multi-currency view showing conversions to all starred currencies at once. It offers 90-day historical rate charts with gradient fills, cubic curves, and trend colors, along with interactive long-press tooltips and date range tabs for 7D, 30D, and 90D views. A home screen widget with Material You dynamic colors works with any currency pair. Privacy features include no analytics or tracking, cloud backup disabled, and network logging fully disabled in release builds. The only outbound traffic is periodic rate syncing; no conversion requests are ever sent. The app is built with Kotlin, Jetpack Compose, MVVM architecture, Hilt, Room, Retrofit, and WorkManager, and is distributed under AGPLv3 via F-Droid.