That's right. Using StockPad doesn't cost anything.
We're hobby stock investors ourselves, and we initially built StockPad as a side project for our own use.
Once we'd finished, though, we thought others might want to use it too. We pay our rent doing other things — so we've made it free to use.
We can't promise it will be free forever and ever. But if we ever start charging, we guarantee two things:
You will know well in advance.
The price will be near-symbolic. We're thinking perhaps 5 €/$ per year. Yes, that's right. Just a few cents per month.
Enjoy — and good luck with your investments.