I created a currency converter, which supports managing frequently used currency type.
It also supports one-to-many conversion.
The exchange rate will update on a daily basis.
You can find more instructions at here. https://github.com/Ericlee0210/alfred-currency-converter-workflow
You can also download the workflow at here. https://github.com/Ericlee0210/alfred-currency-converter-workflow/releases
I would appreciate it if you can give me some feedback.