An invoicing app integrates with your Contacts. An invoicing app keeps a log of all invoices submitted so you can mark them as they are paid and then it lists all outstanding invoices. It keeps track of clients and lists invoices per client. It keeps track of projects and lists invoices per project.
Look, I appreciate your effort, but you really need to look at what people are asking and if you don't have info relating to what they are asking, you shouldn't waste their time replying and then having them explain themselves.
I know about spreadsheet apps. I've used them for decades. I asked about invoicing/billing apps.
I know Final Cut Pro X is not a billing/invoice support forum, I just figured there were a lot of freelancers here who have experience with an app for the Mac for invoicing/billing.
If anyone has experience with an app like that, please feel free to promote it.
Thank you.