Invoice quick is the fastest way I know on how to make invoices on the fly. I like how it is very easy to track invoices and send for payment. I also noticed that there are many integrations to actually use it as a place were your customers can easily pay for invoices, havent used this feature but seems simple enough. Review collected by and hosted on G2.com.

I like how the free version only limits to 3 customers, but understand that they need to monetize as well. Review collected by and hosted on G2.com.