It takes a bunch of JSON files that define info about my clients, as well as my own business details.
It then uses some of those JSON files to generates a PDF for the invoice, which it attaches to an email pre-populated with all the details, including the client’s finance email address, etc., which I just need to double check and send.
Might be useful for freelancers having multiple clients billed using various billing methods (hourly, results based, etc.)