JFX Konwerter is a portable JavaFX-based unit converter.
The program supports 234 units across multiple types: area, currency, data, data transfer rates, energy, length, mass, number bases, power, pressure, temperature, time, velocity and volume.
The currency converter can work from a local database of 31 world currencies, rather than requiring an internet connection. We're not sure how often you'll urgently need to convert Euros to dollars, when you don't even have a phone signal, but the ability is there.
After you've selected the conversion type, the program works much like any other converter you've ever used. Choose "Temperature", select the starting unit (Celsius, Delisle, Fahrenheit, Kelvin, Newton, Rankine, Reaumur, Romer), the destination, type a value and view the results.
Although we had no great problem with any of this, the interface lacked polish and it's not as easy to use as it could be. Lists aren't always sorted correctly (base 18, base 19, base 2, base 3), the button tab order is incorrect, workflow isn't intuitive (you can't choose a unit and start typing right away), there's no one-click option to copy a result to the clipboard, and no history to see multiple results.