Every few weeks someone finds Cake Budget by searching some version of “app like Simple bank” or “safe to spend app,” and I know exactly what they’re looking for, because I was looking for it too.

Simple was an online bank that, for most of a decade, did one thing better than anyone has since: it answered the question “how much can I actually spend?” with a single number, and it kept that number honest without you doing anything. Then in 2021 it was shut down, and its customers were handed a standard checking account with none of that.

This post is for those people. First, what Safe-to-Spend actually did, because the details are the point. Then why the banking replacements never got it right. Then how I rebuilt it on top of whatever bank you already use, which is what Cake Budget is. That last part is the pitch, disclosed.

What Simple got right

Simple’s home screen didn’t lead with your balance. It led with Safe-to-Spend, which was your balance minus two things: Expenses (money set aside for upcoming bills) and Goals (money set aside for things you were saving for).

The magic was in how those two got funded. You set up each Expense and Goal once, with an amount and a schedule tied to your paydays. When a paycheck landed, Simple moved money into each Expense first, then each Goal, automatically. Whatever was left was Safe-to-Spend.

So the number was always true. Rent money was reserved the day you got paid, not the day rent was due. The vacation fund grew without a transfer. And when you looked at the app at the grocery store, the number you saw already had everything spoken for taken out of it. You could spend it without doing math.

That’s envelope budgeting, the method from the cash-and-envelopes era, with the tedious parts (the envelopes) automated by the bank itself. Simple never called it that, which is part of why people who loved it didn’t know what to search for after it closed.

What happened

Simple was acquired by BBVA in 2014 and ran as its own brand for years. In January 2021 BBVA announced Simple would close. Accounts were migrated to BBVA USA that spring, and a few weeks later BBVA USA was folded into PNC.

What customers got at the end of that chain was a normal checking account. No Expenses, no Goals, no Safe-to-Spend. The balance was the balance again, and the money that used to be quietly reserved for rent was back in the pile.

Why the replacements never got it

Plenty of banks now offer some version of “buckets” or “pockets.” Ally has buckets. Some fintech checking accounts let you split a paycheck across sub-accounts. In the UK, Monzo’s pots and salary sorter are the closest living relative.

They mostly miss two things.

They don’t compute the number. Buckets let you set money aside. They don’t put “balance minus everything set aside” at the top of the screen as the thing you look at. You still have to do the subtraction, and the subtraction was the whole feature.

They only work at one bank. Simple’s model required the bank to be the budget. That’s clean when you’re a Simple customer and useless when your money is at Chase and your credit card is at Capital One, which is most people.

There’s a deeper problem with bank-as-budget: it can be shut down. Simple’s customers didn’t lose a feature; they lost their budgeting system when a bank made a corporate decision. I wanted the number back, and I wanted it to survive my bank.

How I rebuilt it

Cake Budget is Safe-to-Spend rebuilt as a layer on top of your existing accounts rather than as a bank.

The vocabulary is different but the mapping is exact:

Simple’s Expenses and Goals are Cake’s slices. An Expense slice with a due date fills toward that date. A Goal slice fills toward a target amount.
Simple’s payday funding is a Cake funding schedule. Tell it when you get paid and what to set aside; when the paycheck lands, each slice gets funded, automatically.
Simple’s Safe-to-Spend is Cake’s Safe to Spend: the sum of your account balances minus everything sitting in slices. Same formula. Same place on the screen.

Two things Simple didn’t have. Safe to Spend in Cake is a traffic light: green above a threshold you pick, amber in between, red below, with a calm sentence under it instead of a lecture. And there’s a 14-day forecast of the bills and paychecks headed for your accounts, so you can see the number’s future as well as its present.

And one honest difference. Cake isn’t a bank, so the envelopes are virtual. When a paycheck funds your rent slice, nothing moves between real accounts; the app reserves that money on paper and subtracts it from what it tells you is safe. In practice this works the same way Simple did, because Simple’s Expenses were also just a ledger inside one account. But if you specifically want money in separate real accounts with separate balances, Cake’s model isn’t that, and a bank with buckets might suit you better.

Who this is for

If what you miss about Simple is the design of the bank, the card, the customer service, I can’t give you that, and neither can anyone; that company is gone.

If what you miss is the number, one figure at the top of the screen that already has rent and the vacation fund taken out of it, and the fact that it stayed true without your doing anything, that’s exactly the thing I built, and it works on the bank you already have.

Common questions

What was Simple’s Safe-to-Spend, exactly? Your account balance minus money set aside in Expenses (upcoming bills) and Goals (savings), with both funded automatically from each paycheck. It was the one number Simple wanted you to look at instead of your balance.

Why did Simple shut down? BBVA, which acquired Simple in 2014, announced the closure in January 2021 and migrated accounts to BBVA USA, which PNC then acquired. Simple’s budgeting features didn’t survive the migration.

Is there a bank that works like Simple did? Not in the US in the same integrated way. Several banks and fintechs offer buckets or sub-accounts, but none put an automatically computed safe-to-spend number at the center of the experience.

Does Cake Budget connect to my existing bank? Yes, through Plaid for most US and Canadian banks, with SimpleFIN as a second option for banks Plaid struggles with. It reads balances and transactions; it never moves your money.

If you’ve been carrying a Safe-to-Spend-shaped hole since 2021, Cake Budget is the same formula on your own accounts, with a traffic light on top. Free for 14 days, no card required.