What the link means
tincount has no accounts, so a link does the job a password would. That is a real trade, and here is the whole of it.
Before you share, nothing has left your device
The list on the front page lives in your browser. No request is made and nothing about your kitchen exists on our server until you press Share this list.
The link is the lock
A shared list gets a 22-character key — 128 random bits, like a shared calendar link. Nobody guesses it. Anyone who holds it can read the list and change a count, and that is the point: a teenager with a bag of mince has to scan a sticker, not make a password.
Known weaknesses, stated rather than hidden: the key travels in the web address, so it reaches browser history and server access logs; it is printed on the QR stickers, so whoever can read a bag in your freezer can read the list; and it cannot be revoked. If a link gets out, start a new list.
What is in the list
A word and a number for each thing, where it lives, when it was last topped up, and whatever first name somebody typed for themselves. No email address, no phone number, no address, no photographs. Nothing is bought, ordered or paid for here.
Two phones, one freezer
Changes are reconciled last-write-wins per thing: the newer change to a tin of beans wins the whole row. Two people changing the same thing in the same minute keep one of the two numbers, not both. That is the right trade for a shopping list and the wrong one for a bank, which is why this never touches money.
The caps
300 things and 200 history lines per list, 30 new lists an hour from one address, 600 changes a quarter-hour per list. Enough for a chest freezer and a pantry; not enough to be worth farming.
Barcodes
A barcode lookup goes straight from your browser to Open Food Facts. It never passes through us, so we never see the number. Their data is used under ODbL and credited on the page.