This is not your average currency converter, instead it converts currencies automatically.
Setup:
Install the app and enable the app extension in the system settings.
Start the app. In the settings window, select your target currency and one or more currencies to convert from.
Run:
Open Safari, Text Edit or another extension enabled application, select some text with prices to convert, click the disclosure button that appears. A secondary window will be shown, containing the found prices with original values and converted values. The conversion is done using the displayed currency unit.
Also, you can force all numbers in the selected text to be converted from one currency to another. It is convenient when there is no currency unit shown.
The currency quotes are updated on demand and stored for offline use. At the first time of use you must be connected to the internet to get the quotes.
Known limitation: The disclosure button does not appear on some web pages. That is a problem beyond my control.
Safari users, check out my Safari extension Direct Currency Converter at https://safari-extensions.apple.com/details/?id=ax.joint.dcc-3X77WF8NVX
