CartEncore isn’t a budgeting app

The thing a monthly total cannot show you

I have kept my own household’s receipts for about nineteen months — 208 of them. Somewhere in there is a 100 g bar of Lindt Excellence 70%, which we buy most weeks.

We buy it on promotion. Not occasionally: it appears on 29 receipts, and on 24 of them there is a discount printed on the line. So the story in this house is “we always get that one on promotion”, and the story is true.

Here is what the receipts do not say. Not one of them says what the bar cost the last time, or the time before. Each is a true record of one afternoon: a price, a discount, a total. Put twenty-nine of them side by side and the shape of the thing is somewhere in the sequence — but no single receipt in that pile contains it, and nobody reads a pile.

No single trip would have made anyone notice. Every one of them felt like a good day.

The bar is laid out purchase by purchase — what one product actually cost you over time →

And none of it was visible to a budgeting app, which is not a failing on its part. To the bank it was the same supermarket, the same weekly charge, the same category, month after month. The number that changed was inside the receipt, and the receipt was in a drawer.

Why this exists

There is a quieter version of the chocolate story, and it is the more common one. A tub of butter I have bought twenty times went up three times over five months — five cents, then ten, then five — and then sat still for the next eleven. Under nine per cent in total, in moves nobody notices. What you notice, a year later, is that butter costs more, without being able to say when that happened or by how much.

That is the shape of almost everything in a supermarket. Prices do not announce themselves. They move a little, wait, and move again, and the only place the whole sequence is written down is on a series of receipts nobody keeps.

GROCERY MARKET  $86.40 is what your bank hands your budgeting app. That line is all it gets. CartEncore starts from the receipt behind it — the seventeen items that added up to $86.40 — and then keeps them, so that the eleventh time you buy the same butter, the previous ten are still there.

I spent years running a site that told people where groceries were cheaper. It worked, and it taught me that I knew the price of milk across seven chains and had no idea what my own house had spent on meat the year before. CartEncore came out of that second part.

The receipt behind that line looks different in every chain — what US stores actually print →