QuickBooks is built for businesses that need full accounting — books, payroll, tax prep, multi-user access — with invoicing as one piece of a much larger system. That depth is exactly why it's overkill if invoicing is the only thing you need right now.
SMBkits' invoice generator has none of that depth, on purpose: no accounting ledger, no payroll, no subscription. Enter your business and client details, add line items, and download a PDF. It's meant for the moment you need to bill someone without opening a whole accounting system to do it.
This pattern shows up a lot in small business tooling generally: a category leader (QuickBooks, in this case) builds one feature as part of a much bigger paid platform, while a free, single-purpose tool does that one feature without the rest of the system attached. It's the same trade-off you'll see comparing QuickBooks' employee cost calculator to a standalone one, or comparing any 'send invoices for free' search result to full accounting software.
If you're already scaling toward needing real bookkeeping — multiple employees, tax filing, multi-user access — QuickBooks' subscription earns its cost. If you're a freelancer or small operator sending an occasional invoice, that subscription is solving a problem you don't have yet.