Why I am building Billy

My first requirement was: it has to look good

For most people an invoice is a form. For me it was the last thing a client sees of me — after weeks of work that was about design the whole way through. An invoice that looks like it came out of a 2009 accounting suite ruins that last impression.

So I looked at the tools. They were either cluttered or overloaded, usually both. A good number of them I never seriously tried: you could tell from the screenshots that nothing would come out the other end that I would want to send.

So I kept making them myself. Every single one, by hand.

The day the numbers stopped adding up

If you build your invoices by hand, you keep the numbering in your head, in a file, in the filename. That works for a while. In my case it worked right up until I sent out two invoices carrying the same number.

That is not a cosmetic slip. An invoice number may be issued exactly once — which sounds tidy until you have to explain to a client which of the two invoices is the real one. What belongs on an invoice and why is in the guide to the mandatory details.

That was the moment it clicked: I had spent years solving a problem by hand that software should be solving. I just did not want any of the software.

I have made just about every mistake there is

Mixed-up numbers. Wrong tax rates. Reverse charge misunderstood — the case where no VAT belongs on the invoice at all, but one specific sentence does.

I am not telling you this because it makes a good anecdote. I am telling you because that list is the feature list. Every one of those mistakes is now something Billy simply does not let you make: the software issues the numbers, suggests the tax rate, and will not switch reverse charge on at all without the recipient's VAT ID.

That is the difference between a form and a tool. A form accepts whatever you type. A tool knows what you are doing.

What I actually wanted: Shopify, not accounting software

Accounting software decided a long time ago that “serious” means the same thing as “complicated”. Nested menus, vocabulary borrowed from a tax firm, a chart of accounts before you have done anything. People who work with it either learned it or have someone who did.

So my benchmark was never another invoicing tool. It was Shopify. Not the features — the feeling: you open it, it is obvious what to do, it looks good, and you are done in a minute. That is exactly what I wanted for the moment you write an invoice.

Where Billy is today

Billy is an invoicing app for freelancers and small businesses in Germany, Austria and the US. Templates you send without hesitating. The rules — mandatory details, small-business status, reverse charge, payment reminders — live inside the product so they do not have to live in your head.

Alongside that, an AI assistant that creates, sends and chases invoices — but never does anything without showing you exactly what it is about to do first. That part matters to me: the software can do the work. The decision stays yours.

Billy is not finished, and I would not claim it ever will be. But the direction has not changed since the day with the two identical numbers.

I am not a tax adviser and not an accountant. I am someone who sent the wrong invoice one too many times and eventually decided the software should know this, not me.

— Luca, founder of Billy