Money saving apps for Mac are usually the phone app in a window, or a web page in a wrapper, and nearly all of them start by asking you to connect a bank account. Keep the Diff is a native macOS app, and it cannot connect to your bank because there is no bank integration in it at all.
What it does
You log two numbers: what you were ready to spend, and what you actually spent. The difference is the Diff, and it is recorded as money you kept. It adds up by week, by month, and toward whatever you are saving for.
Buy the thing anyway and nothing happens. There is simply no Diff that time. No budget to exceed, no streak to break, and no red number, because the lowest a week can read is zero.
On the Mac specifically
- A real Mac app, built with Compose Desktop and shipped as a normal DMG. Drag it to Applications and open it. That is the whole install.
- Signed and notarized by Apple, so it opens without a Gatekeeper warning and without right-click-Open theatre.
- It updates itself. The download from this site checks for a new version and installs it, so you are not hunting for a DMG in six months.
- Premium can be bought right in the app. Click Premium, pick a plan, pay on Stripe's own page in your browser. It is cheaper here than in an app store, because a direct sale pays no platform commission.
- Also on the Mac App Store, if you would rather everything came from there.
Your numbers stay on your Mac
No account, no sign-in, no analytics, no tracking and no advertising identifier. Nothing you log leaves the machine. The only time the app talks to the internet at all is if you buy or unlock Premium, and that request carries a short code and a receipt number, never anything you have written down.
It is not Mac only
The same app runs on iPhone, iPad, Apple Watch, Windows, Android and Wear OS. One Premium subscription covers every device you own, so buying it on the Mac unlocks the phone too.