Name: Keep the Diff
Author: Lee

If you are planning a no spend month or a no buy year for 2027, you will find a lot of apps that promise to help. They count different things. Some count days, some count dollars, some help you pause before you buy. Picking the right one depends on what you want to see at the end of the challenge.

This list covers seven apps and one paper option, grouped by what each does best. The app details come from each app's App Store listing, checked in October 2026. Small new apps change fast, so confirm in the store before you install.

What to look for in a no spend challenge app

Four questions sort most of the choices.

What does the app count? Days, items, or money. A day count is simple. A money total shows what the challenge was worth.
What happens when you slip? Some apps reset a streak. Others forgive a day. A few have no streak at all. A challenge that is easy to restart after a bad week is easier to finish.
Can the app record a partial win? Buying the $30 version instead of the $60 one is a good decision in a low buy year. An app that only knows yes or no cannot show that partial win.
Does the app need your bank? A bank connection is not needed to track what you chose not to spend. Several apps below work without one.

The apps, side by side

Checked October 2026 from each App Store listing. Other platforms may exist, so confirm in the store.

App	What it counts	Slip handling	Bank connection
Keep the Diff	Money kept: planned spend minus actual spend	Nothing resets. Buying anyway is logged like any other decision.	None, by design
NoBuy: No Spend Challenge Game	Days, as a streak	A freeze keeps the streak alive after a slip	None, per its listing
Stop Impulse Buying	A no spend calendar, plus a 52 week savings challenge	Listing describes streaks and progress over time	None listed
mallow	Items and money you chose not to buy	Wishlist cooldown timer before you decide	None listed
Cartless	Days marked as a skip or a buy, with a running total	Each day is marked on its own	None listed
Mora	Daily check-ins across challenge types	A rest day covers a forgotten day. Buying is a valid outcome, per the listing.	None, per its listing
Unspent	What you and your group resisted	Built around a shared challenge	None listed

You can read the listings yourself: NoBuy, Stop Impulse Buying, mallow, Cartless, Mora and Unspent.

Best for a daily habit: NoBuy

NoBuy turns the challenge into a daily tap. You pick a strict no buy or a low buy, choose the categories you are cutting, and answer one question each day. Its listing says a freeze protects your streak after a slip, which is a kind design choice. If you like a game with a plant that grows, this is built for you. The trade is that the headline number is days, so a day that went well but included a small purchase has no way to show up as partly good.

Best for a calendar and a 52 week plan: Stop Impulse Buying

Stop Impulse Buying combines a no spend calendar, a 52 week savings planner and a set of questions to answer before a purchase. If you want several challenge formats in one place, that is the draw. The 52 week plan in its listing saves up to $1,378 over a year. If you are weighing that style, 52 Week Money Saving Challenge is a single-purpose app for it.

Best for letting a want cool off: mallow

mallow asks you to write down what you did not buy and watch the savings add up, and it has a wishlist cooldown timer: write the want down and wait. It is the closest match to the idea behind Keep the Diff among these apps, since both record the value of what you skipped.

Best for pausing in the moment: Mora

Mora supports a reset week, a no spend month, a low buy month, a no fashion season or a no buy year. When you want something, you can start a ten minute pause with a breathing circle and decide afterward. The listing is explicit that there is no bank connection and that buying the thing is a valid outcome, which keeps the tone free of guilt.

Best for doing it with other people: Unspent

Unspent is the one in this list built around a group. You start a challenge, invite friends, and everyone sees what the others resisted. If accountability helps you, that is worth trying. If you would rather keep your numbers private, look at a no spend challenge with a partner, without the scoreboard.

Best for a money total and a goal: Keep the Diff

Keep the Diff counts one thing: planned spend minus actual spend equals the Diff. You log what you were ready to spend and what you actually spent. Skipping a purchase is a Diff equal to the full amount. Buying a cheaper version is a smaller Diff. Nothing resets and there are no streaks, so a rough week does not erase the total. There is no bank connection.

The free plan logs without limits. Premium adds sync, multiple goals with photos, widgets, the watch app and recurring Diffs. Version 1.4.0 added a 52 week challenge and a Not sure yet option for purchases you cannot decide on. Be aware of what it does not do: there is no group challenge, and it does not read your accounts, so every entry is typed by you.

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.

A paper tracker still works

A printed sheet on the fridge is a fine no spend tracker, and it needs no setup. If you write the amount next to each skipped purchase, it becomes a money tracker as well. There is a printable savings tracker you can use.

How to choose

You want the simplest daily habit: NoBuy or Cartless.
You want a few challenge formats together: Stop Impulse Buying.
You want to pause before you decide: mallow or Mora.
You want company: Unspent.
You want to see the money, count partial wins and aim it at a goal: Keep the Diff.

For a deeper look at the features that matter, read no spend challenge apps compared and no buy tracker apps compared.

Best no spend challenge apps for 2027, compared