Get credit for the money
you decided not to spend.
You talk yourself out of things all the time. Nothing records it, so it never feels like progress. Keep the Diff records it: what you were ready to spend, what you actually spent, and the difference kept as yours.
Beach vacation
$858.00
of $1,200.00
$258
Log a Diff
What did you skip, save, or swap today?
Keep the Diff
This week
$258
5 better decisions
Recent
- Concert ticket I talked myself out ofToday · Entertainment+$68.00
- Cooked instead of the usual Friday orderYesterday · Dining+$32.00
- Skipped the airport coffeeTuesday · Dining+$14.50
- Running shoes, current pair is fineMonday · Shopping+$129.99
- Walked half of itMonday · Transport+$13.51
$258
5 better decisions
Synced just now
Why I Created Keep the Diff
Hi- I'm Lee. I built Keep the Diff because every budgeting app I tried started by asking to connect my bank, and then spent the rest of its life telling me what I had done wrong. Red numbers. Categories I overspent. A monthly verdict I already knew.
What none of them ever recorded was the part I was actually proud of: the takeaway I talked myself out of, the jacket in the tab I closed, the second round I skipped. Those decisions are the whole reason there is money left at the end of the month, and every app treated them as nothing, because nothing was spent.
So Keep the Diff records the decision instead of the transaction. Two numbers, and you can try the whole thing right here without installing anything. There is no bank connection and no account needed, because the app only ever knows the numbers you type. If you buy the thing anyway, nothing scolds you: there is no streak to break and no red number to go into.
Getting started is easy. Say what you were ready to spend, say what you actually spent, and keep the difference. It adds up by week, by month and toward whatever you are saving for, and you can put it on your home screen and your wrist so the total is in front of you without opening anything. When you know what is coming you can set the number before you spend it and let the app ask you afterwards. You can check out some of the common decisions other people log.
Keep the Diff is a free download on iPhone, iPad, Mac, Apple Watch, Windows and Android. There's also a common questions section for a full breakdown of how the app works, and more about me and why I built this.
You can use the Message Me button with any questions and I'll get back to you within 24 hours. Keep the Diff made me better with money without making me feel worse about it, and I look forward to hearing what you keep.
Cheers -Lee
You can also check out my other apps Reveal the Dream, The Long View, MyLinedChart, Still Dock, Copy Shelter, and Prompt Petal.
Common decisions logged
Use these as an idea to get you started on keeping your own diffs.
-
Dining
Cooked instead of the usual Friday order
+$32.00 -
Entertainment
Concert ticket I talked myself out of
+$68.00 -
Shopping
Running shoes, current pair is fine
+$129.99 -
Dining
Skipped the airport coffee
+$14.50 -
Transportation
Walked half of it instead of the whole fare
+$14.00 -
Dining
Second round, went home instead
+$42.00 -
Groceries
Store brand, not the name
+$17.00 -
Shopping
Refurbished, not new
+$61.00 -
Entertainment
Matinee instead of the evening show
+$45.00 -
Subscriptions
Canceled the one I never opened
+$11.99
Nothing. There is no red number to go into.
Buy the thing and there is simply no Diff to record, so nothing is added that week. That is the whole consequence. The app has no budget you can exceed, no streak to break and no color for disapproval: the lowest a week can ever read is zero.
That is not softness, it is what makes the number trustworthy. An app that punishes you for a bad week is an app you stop opening after a bad week, and then it knows nothing about you at all. This one is only ever counting the times you chose the cheaper thing, and it is happy to wait.
Spent less than you planned rather than nothing at all? That counts too. Ninety dollars planned and forty spent is a fifty dollar Diff.
Log it, watch it add up, give it a goal
Log what you skipped with two numbers. Home adds up your week, History keeps every week, Goals gives the money somewhere to go, and the recap shows where it came from.
-
This week
The number, and what it is made of
-
Log a Diff
Two numbers, and it counts the gap
-
History
By week, with every week's total
-
Goals
Send the Diff at something you want
-
Weekly recap
A card you can share, or not
-
Dark mode
Follows your system, on every platform
Know what you were ready to spend, because you said so first
Most of the app is about a decision you already made. Plan a spend is the other way round: put in what you are ready to spend on something coming up, say roughly when to ask about it, and get on with your evening.
When the time comes the app asks one question, "what did you actually spend?", and the Diff is the gap. Sixty planned and forty spent is a twenty dollar Diff, measured against a number you set before dinner rather than one you tried to remember afterwards.
Until then Home counts down to it, so the question never arrives out of nowhere, and the same countdown rides along onto the widgets and watch faces if you have Premium. One switch in Settings turns it off everywhere. Planning a spend and answering the check-in are free, on every platform.
On your wrist, your home screen, and both of your computers
Keep the Diff is also on your watch, phone screen and even on your computer, with the same countdown to your next check-in on each of them.
Free vs Premium
Start free. Premium adds full history, categories, unlimited goals and App Lock.
Free
- Unlimited decisions, on every device you own
- This week's Diff and this month's
- The last 14 days of history
- The weekly recap card, on iPhone, iPad and Mac
- One goal at a time
- Dark mode and adjustable text size
- No account needed, no bank connection, no ads
Premium Cheapest bought here.
- Everything in Free, plus
- Your full history, however far back it goes
- CSV export of every decision
- Categories, and where the Diff actually comes from
- Unlimited goals, each with a photo
- Home screen widgets and the Lock Screen entry
- Apple Watch
- One subscription covers every device you own
Get Keep the Diff
Free on Apple, Android, and Windows. Sign up here for the best pricing on Premium.
| Plan | Feature | iPhone | iPad | Mac | Apple Watch | Windows | Android |
|---|---|---|---|---|---|---|---|
| Free | Log a Diff | Included | Included | Included | Included | Included | Included |
| This week and this month | Included | Included | Included | Included | Included | Included | |
| 14 days of history | Included | Included | Included | Not available | Included | Included | |
| Weekly recap card | Included | Included | Included | Not available | Not available | Not available | |
| One goal | Included | Included | Included | Not available | Included | Included | |
| Dark mode and text size | Included | Included | Included | Included | Included | Included | |
| Premium | Full history | Included | Included | Included | Not available | Included | Included |
| CSV export | Included | Included | Included | Not available | Included | Included | |
| Categories and breakdowns | Included | Included | Included | Not available | Included | Included | |
| Unlimited goals | Included | Included | Included | Not available | Included | Included | |
| Widgets and Lock Screen | Included | Included | Not available | Not available | Not available | Included | |
| The watch app | Not available | Not available | Not available | Included | Not available | Included |
Your money stays yours to know about.
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 is kept on your own device and we never see it: the numbers you type are the only numbers the app has. No account is needed, and the app has no analytics. Read the whole privacy policy, which is short.
Frequently asked questions
Common questions about saving money without a budget, and how the Diff works. There is more in the blog, and for anything else visit Support or read the Privacy Policy.
What is Keep the Diff?
An app for iPhone, iPad, Mac, Apple Watch, Windows and Android, built around one subtraction. You log 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.
Is this a budgeting app?
No, and it is deliberately the opposite. A budget tells you what you are allowed to spend and scolds you when you go over. Keep the Diff never tells you what to spend. It only records the times you chose the cheaper thing, which is the part every other app treats as nothing because nothing was spent.
Do I have to connect my bank?
No, and you cannot. There is no bank integration in the app at all. It cannot read your transactions, does not ask for credentials, and never makes you sign in. The only numbers it has are the ones you type.
What if I buy the thing anyway?
Nothing happens. There is no Diff to record that time, so nothing is added, and that is the entire consequence. No streak breaks, nothing resets, and no number goes red. The lowest a week can read is zero.
What if I spent less rather than nothing?
That still counts, and it is the common case. Ninety dollars planned and forty spent is a fifty dollar Diff. The app has a "Didn't buy it" button for when the actual number is zero, because that is the fastest path, but any pair of numbers works.
How long does logging one take?
Three taps plus the digits. That matters more than it sounds: the moment you decide not to buy something is usually a moment you are standing in a shop, and an app that takes a minute is an app you use once.
What is a planned spend?
A number you set before you spend, rather than after. Put in what you are ready to spend on something coming up, pick later today, tomorrow morning or in three days, and the app asks what you actually spent when that time arrives. The Diff is the gap between the two. It is one evening at a time, not a budget: there is no envelope, no monthly allowance and nothing to roll over. Planning and answering are free.
Is it really free?
Logging is free forever, on every platform, with no ads and no limit on how much you log. Premium adds full history with CSV export, categories, unlimited goals, widgets and the watch app. One subscription covers every device you own.
What does Premium cost?
$4.99 a month, or $3.33 a month billed annually, in the app stores. Bought directly here it is $3.99 a month, or $2.92 a month billed annually, because a sale on this site pays no app store commission and the difference goes to you rather than to Apple or Google.
Does my data sync between devices?
Your decisions are stored on the device you logged them on. On Apple and Android they are included in your own iCloud or Google device backup, the same as any other app's data. Premium is what follows you between devices: one subscription unlocks all of them.
Can I get my data out?
Yes. Premium exports every decision you have ever logged as a CSV file, which opens in any spreadsheet. It is your data and there is no lock-in.