Keep the Diff
Behavioral money, not budgeting
You talk yourself out of things all the time. Nothing records it, so it never feels like progress. Keep the Diff records it.
In development. Coming to iPhone, iPad, Mac, Apple Watch, Android and Windows.
What it is not
A budget tells you what you are allowed to spend, and it is a scold when you go over. A no-buy challenge asks you to say no to everything and be pleased about it.
Keep the Diff does neither. It never tells you what to spend, it never links your bank account, and it never shows you a red number. It only asks what you were ready to spend and what you actually spent, and then it keeps the difference where you can see it.
How it works
The dinner you nearly ordered. The jacket in the tab you closed.
Often nothing. Sometimes less. There is a "Didn't buy it" button for the common case.
The difference is yours. It adds up by week, by month, and toward whatever you are saving for.
Pricing
Logging a decision, seeing your Diff and watching the week add up costs nothing, forever. Premium is for people who want the long view of it.
Where it runs
The decision happens in a shop, on a couch, in a checkout flow. The app has to be wherever that is, which is why it is being built for all of these rather than a phone and a promise.
Privacy
Keep the Diff does not connect to your bank. There is nothing to link, no credentials to hand over and no transaction feed to read. Everything you log lives on your own device, and the numbers you type are the only numbers the app has.