Put something in the tin

Nothing. No account, no badge, no faster analysis, no feature that was hidden before. There is deliberately nothing to hand over, because there is nothing being withheld.

Saying so plainly matters more than the money. A donation laid out like a purchase — tiers, a menu of amounts, a list of what each one unlocks, a monthly box already ticked — tells you that you are buying something, and you would be right to expect it. That is why there is one button and no options: you are not buying anything here.

Grading a game costs nothing to serve — Stockfish runs on your own processor, so the hundredth game is as cheap as the first. What is not free:

• Bandwidth. The engine is about seven megabytes, sent to every visitor who has not been here before.
• A domain, and whatever hosts it. Small, but not nothing, and it arrives every month whether anyone visits or not.
• Time. The unglamorous half — checking every lesson position against an engine, the opening book, the thresholds that stop the pattern miner from making things up.

The button takes you to a page Buy Me a Coffee hosts, on their own domain, and the card details are typed there. The amount is yours to pick, and so is whether it happens once or every month — both are offered on that page, and the monthly one can be cancelled there whenever you like.

There is no default and no box already ticked on this side, because this side does not take the money. A one-off is the ordinary case and the one this page is written for.

This site never sees your card: the payment happens on the donation page, not here, and nothing on this site handles a card number.

Then do not, and nothing about the app changes. Telling somebody about it, or opening an issue when a move is graded wrongly, is worth a good deal too.