Sweep
The list meets you at the store.
An errand is a place, plus a thing to do there.
Sweep groups errands by the kind of store that handles them. When you are near one of those places, the list shows what is waiting there.
The moment
You are at the post office, returning a package. The grocery store is next door. Dish soap has been on your list since Tuesday.
Sweep knows dish soap is a grocery errand, and it knows the grocery store is the one next door. So it says so while you are still standing there.
What it does
Type an errand the way it occurs to you — dish soap, a lemon, cash, a package to return. Sweep works out which kind of store it belongs to.
Open the map when you are out. Nearby stores show what they can handle from your list, so you can see which stop is worth making.
Walk in with the list for that stop already gathered.
How it works
Your list stays on your phone, and there is no account to make.
To sort an errand into a category, Sweep sends the words you typed to my server, which works out what kind of store the errand belongs to and sends the answer back. Those words are the only thing that leaves your phone, and I keep no copy of them. If the connection fails, the errand arrives without a category and you choose one yourself. The privacy policy explains it in full.