Offline Currency Converter

A privacy-focused currency converter for Android that works completely offline. No account, no tracking, no analytics — just exchange rates in your pocket.

The app fetches exchange rates from the free Frankfurter API (powered by the European Central Bank) and stores them locally using Room. Once synced, all conversions happen entirely offline. You can configure the sync interval in settings (6h, 12h, 24h, 48h, weekly, or manual only), and a background WorkManager job keeps rates up to date.

Features

• 160+ currencies — all ECB reference rates
• Favorites — star your most-used currencies for quick access
• Multi-currency view — see conversions to all your favorites at once; favorites stay visible when the amount is cleared
• Rate trend charts — 90-day historical charts with gradient fill, cubic curves, and trend colors
• Interactive charts — long-press for crosshair tooltip with date and rate
• Date range tabs — switch between 7D, 30D, and 90D views (persisted across restarts)
• Home screen widget — Material You dynamic colors, works with any currency pair
• Sync status — colored badge shows how fresh your rates are
• Bundled flags — country flags are built into the app, no network loading
• Privacy first — no accounts, no tracking, no network permissions at runtime