> but on the side of tracking which invoices are open vs. paid, which ones are aging, whether there are discounts that can be applied for early payment, and of course integration with whatever accounting tools you're using.

In my experience

- you either did work for someone who does pay invoices, or doesn't

- if you are boned when the last invoice isn't paid, you are in very deep trouble. That means you're not in the "invoicing" business, you're in the flipping business

- so optimizing for the best case, well, you don't need to really track this stuff, or offer discounts for early payment or whatever

> of course integration with whatever accounting tools you're using.

Of course, you could be charging enough money that you don't really have to think about your costs.

The kind of person doing that has the bandwidth to install and use open source tools.

So ironically, the person who is arguably the best B2B customer, making tons of money, lots of bandwidth, pretty sophisticated, is the person most likely to use a simple open source invoice PDF generating tool. And that's why these things get adoption. That's why open source thrives.

I don't know if Invoice Dragon will make money but its users are necessarily going to be great. Because the person who gets the most out of it is running a great business.