Name: Keep the Diff
Author: Lee

Impulse buying is a timing problem. The want arrives, and the purchase is one tap away. Apps that help work on that gap in different ways, so it helps to know what kind of help you are choosing. This guide sorts them into four types and names an app or two in each.

The app details come from each App Store listing, checked in October 2026. Small new apps change often, so confirm in the store before you install.

Type one: the blocker

A blocker adds a pause before you reach a store.

PauseBuy describes itself as a shopping blocker. When you try to open a shopping app you chose, such as Amazon, Temu or Walmart, it steps in first with a short mindful pause and a few questions about the purchase. It also has a way to save an item for later.

Good for: people whose impulses come from opening a specific app.
Worth knowing: it works on the app you chose. A purchase made in a browser or in a store is a different path.

Type two: the cooldown list

A cooldown list makes you write the want down and wait.

mallow has a wishlist cooldown timer and lets you record the value of things you chose not to buy. Stop Impulse Buying includes a decision making guide to use before a purchase, plus a no spend calendar and a 52 week savings planner. Mora lets you pause a want and decide later, with a ten minute breathing pause for the moment the pull arrives.

Good for: wants that fade within a day or a week, which is most of them.
Worth knowing: the app can only remind you. You still have to come back and decide.

If you like the idea but want it without an app, the 24 hour rule is the paper version.

Type three: the tracker

A tracker records what happens so you can see a pattern.

Cartless lets you mark each day's category as a skip or a buy and shows a running total. NoBuy asks one question a day and, per its listing, uses a freeze to protect your streak after a slip.

Good for: people who respond to seeing progress.
Worth knowing: day-based trackers count days and leave out dollars. A day with a planned, sensible purchase can look like a miss. The article on the no spend challenge without the streak that ruins it covers the streak question in more depth.

Type four: the group

Unspent is built around accountability. You start a challenge, invite friends, and everyone sees what the others resisted.

Good for: people who need company to follow through.
Worth knowing: your skips are visible to the group. If privacy matters, that is a trade.

Where Keep the Diff fits

Keep the Diff is closest to the tracker type, with one difference: it tracks money instead of days. Each time you skip or reduce a purchase, you log what you were ready to spend and what you actually spent. Planned spend minus actual spend equals the Diff. The Diff adds up by week, by month and toward a goal with a photo.

It also touches the cooldown idea. Version 1.4.0 added Not sure yet: tap Not sure yet when you log a purchase you cannot decide on, and Keep the Diff asks again when you choose. Skip the purchase and the money counts as a Diff. What it does not have is a blocker, a group challenge or any link to your shopping apps. There is no bank connection, and nothing resets after a slip, because there are no streaks.

The free plan logs without limits. Premium adds sync, multiple goals with photos, widgets, the watch app and recurring Diffs.

Checked October 2026 from each App Store listing.

Type	Example	What it does	What it leaves to you
Blocker	PauseBuy	Adds a pause before shopping apps open	Purchases outside those apps
Cooldown list	mallow, Stop Impulse Buying, Mora	Holds a want while you wait	Coming back to decide
Tracker	Cartless, NoBuy	Shows progress day by day	Dollars, in a day-based tracker
Group	Unspent	Adds accountability	Keeping your skips private
Money log	Keep the Diff	Records the money each decision kept	Pausing before you buy

You can combine them

Nothing says you need one app. A common mix is a blocker for the moment of temptation and a money log for the aftermath. Pausing handles the urge. Logging gives the pause a reward, since the skipped amount shows up on a screen.

How to pick

Notice where your impulses start. If it is one shopping app, try a blocker.
If it is late-night browsing, try a cooldown list.
If seeing numbers motivates you, try a tracker. Decide whether you want days or dollars.
If you do better with company, try a group.

For the cost side, what impulse buying costs in a year works through the arithmetic, and how to stop impulse buying by recording what you didn't buy explains the logging idea in depth.

Keep the Diff is on the App Store and Google Play, and there are downloads for Mac, Windows and Linux on the download section of the home page. You can also try it in your browser first. Premium pricing is on the Premium page.

Apps that help with impulse buying, and what each one does