BPI Tracker uses CoinDesk's Public API to retrieve the Bitcoin Price Index (BPI) value and display it in USD, GBP, and EUR prices. Users can see the current price of Bitcoin by tapping on the Update button. Each time price is updated, the timestamp changes to the latest UTC time. Error messages are displayed in red text above the Bitcoin image. If users want to know more about the app, they can press the info icon in the navigation bar to bring them to the info page. Powered by CoinDesk.