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Expense trackers that don't link your bank, and why manual wins

By , who built Keep the Diff

Mint shut down in March 2024, and a lot of people discovered something they had not thought about while it was running: to use it, they had been handing a company continuous read access to every transaction in their bank account.

Most of the replacements work the same way. Open one and the first screen asks you to log into your bank through an aggregator. If you would rather not, the usual outcome is that you close the app and go back to nothing.

This article is about the other category: expense trackers where you type the numbers in yourself. They are less convenient, they are more private, and there is a reasonable argument that they work better.

What bank linking actually involves

When an app offers to connect your bank, the app almost always reaches the bank through an aggregator, and that aggregator holds a connection that can read your transaction history on an ongoing basis.

That arrangement is normal, widely used, and mostly fine. It also means your complete spending history sits with a company you did not choose, whose name you may not know, and whose future you cannot predict. Mint's shutdown was a reminder that these arrangements are not permanent.

There is a second, quieter problem. An aggregator cannot see cash. If you pay for anything in cash, an automatic tracker has a hole in it and no way of telling you.

Why manual tracking works better than it should

The obvious objection to typing your spending in yourself is effort. The less obvious counterpoint is that the effort is where most of the value is.

An automatic tracker shows you a report of what already happened. You read it afterward, feel briefly informed, and change nothing, because by the time you see the number the decision is weeks old.

Manual entry puts the attention at the moment of the decision. You notice the amount as you commit to it. People who have used both routinely report the same thing: they became more careful under manual tracking and no more careful under automatic tracking, despite automatic tracking having strictly better data.

Here is the real trade. Automatic tracking optimizes for completeness of the record. Manual tracking optimizes for awareness at the point of spending. Only one of those actually changes what you do.

The version that records what you did not spend

There is a variant worth knowing about, because it is the one thing no bank feed can ever do, even in principle.

Every transaction-based tool, automatic or manual, can only record money leaving. The times you decided against something produce no transaction at all: no line in the feed to import or categorize. They are invisible to the entire category.

But those decisions have amounts attached and they are the reason there is money left at the end of the month. So you can run a tracker that records the opposite: what you were ready to spend, what you actually spent, and the difference kept as a running total.

A decision record is only possible manually. There is no data source in the world that knows you nearly bought something, so typing the numbers in yourself is the only way such a record can exist.

What to look for in a private expense tracker

  • There is no bank integration of any kind, optional or otherwise. A feature that is off by default is a setting you have to trust. An app with no integration in it cannot read your account whatever anybody does.
  • No account needed. With no sign-up, you have no password or stored identity to lose in someone else's breach.
  • Local storage you can see. Data on the device, included in your own phone backup, and kept out of any database belonging to the developer.
  • Export. If you cannot get your data out as a CSV, you do not really have it. Export is also your insurance against the app disappearing the way Mint did.
  • An honest privacy page. Look for one that lists what the app actually does. "We collect nothing" is easy to write and easy to outgrow; a page that names each request the app can make has clearly been checked recently.
  • No analytics SDK. Plenty of otherwise-private apps still ship a third-party analytics library, which is a network call to somebody else on every screen you open.

The honest downsides

Manual tracking has real costs and you should know them before switching.

You will miss things. Nobody logs every purchase for long, and if your goal is a complete audited record of your spending, a bank feed will beat you every time. You also lose automatic categorization, balance tracking and net worth, which for some people are the entire point.

And local-only storage means device loss is data loss unless your phone backup is working. That is the price of keeping your history off somebody's server, and it is a real cost.

If you want the complete picture of every dollar, connect the bank. If you want to change how you spend, and you would rather not hand your transaction history to a third party, manual is the better tool for the job.

What we built

Keep the Diff is the second kind: a manual tracker for the money you decided not to spend. It has no bank integration, no account needed, no analytics and no ads. Everything you log is stored on the device, and Premium exports the lot as a CSV.

The app uses the network in two cases, and you choose both: unlocking Premium on a Mac or a PC, which sends a short code and a receipt number and nothing you have written down, and Premium sync between your own devices, which sends a copy sealed on the device with a key that never reaches us. We spell this out because we once claimed there was no networking at all, and that claim went out of date. The longer version is here, and the privacy policy is one page.

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