What do you actually need from an invoice generator?

I've been working on Free Invoice Generator, a simple tool for freelancers and small businesses who just want to create a professional invoice without having to learn complicated accounting software.

While building it, I kept coming back to a simple question:

What are the features people actually care about when creating an invoice?

For me, the essentials seemed to be:

• Creating an invoice quickly

• A professional-looking PDF

• Multiple currencies

• Flexible payment terms

• No unnecessary complexity

• No watermark on the final invoice

But I'm curious what other founders, freelancers, and small business owners think.

What's the one feature you consider essential in an invoice generator—and what's something you've found unnecessarily complicated in existing invoicing tools?

I'd especially love to hear from people who invoice clients regularly.

For anyone interested, this is the tool I'm building: https://freeinvoicefast.com/

I'm mainly here to learn from the community and improve the product based on real-world invoicing workflows.