Case study · Own product · On the App Store

Every bill, marked as paid.

Muuka is an iPhone app that remembers which bills you have paid. It is my first app: from a spreadsheet to the App Store in 15 days. I designed it and built it with AI. I didn’t write the code, but I checked every change on my phone before it went in.

Role: Founder
Platform: iPhone, free
Released: 23 September 2026
Updates: 3 in two weeks

App Store screen: What is still unpaid, at a glance. Home lists this month’s unpaid bills

App Store screen: Paid it? Swipe it right. A bill is swiped and marked paid

App Store screen: Watch the month add up. Paid shows the total so far, by category

01 · The brief

One sentence, before any screen.

For years I kept my bills in a spreadsheet. It worked, but it lived on a desk, and when someone said I hadn’t paid something, I had no quick way to check. The brief started with one sentence, and every idea that added a tap was cut against it.

“I open Muuka and mark a bill paid in ten seconds.”

The brief, and what Muuka is not:

It doesn’t pay bills
It doesn’t connect to a bank
It isn’t a budget
No ads, no tracking

02 · Three designs thrown away

Built, tried and dropped.

With AI, a wrong design costs so little that I could build each idea and try it on my phone instead of imagining it in Figma. A year of squares was lovely and useless for marking a bill paid. Cards true to Figma came next, then a swipeable stack that took two days. What stayed is a plain list: one row per bill, an arrow while it waits, a tick when it’s paid.

The first design: every bill as a row of twelve squares, one per month — 1 · A year in squares

The second design: bordered cards with due days and red amounts — 2 · Cards, true to Figma

The third design: a stack of coloured cards, one bill at a time — 3 · A stack to swipe

03 · The app

One meaning, one look.

Once the list won, the same row went everywhere. An arrow means it waits, a tick means it’s paid, a dashed circle means skipped this month. Home is built to be empty, Paid collects the month, and the Calendar keeps the year to the cent. The store screens are drawn from the app’s own colours and icons, so one command redraws them when the app changes.

Home: the bills still unpaid this month — Home: what still waits

Swiping a bill right to mark it paid — Swipe right to mark paid

Paid: this month’s total and every bill by category — Paid: the month adds up

Calendar: any month opened, with where the money went — Calendar: the year, kept

Adding a bill: name, amount and category — A bill in three fields

A reminder before a due day, in dark mode — Reminders, only if you want

04 · The road to the store

Apple asked, and the answer found a bug.

The part no mockup shows: reminders, deleting your account, signing in with Apple without losing anything, the store listing, and the review. I did every step by hand, one at a time, so I would understand it.

18 SepSent to Apple for review.
19 SepApple asked for a screen recording of the whole app and six answers.
RecordingThe video caught a real bug: after deleting an account, the app stayed on the wrong screen. Two builds later it was fixed and recorded again.
23 SepOn the App Store.
2 weeksThree updates: 132 currencies and a shorter form, fixes after a demo to designer friends, and fixes from my own use.

05 · The product page

A website in the app’s own language.

Same warm paper, same rows, same tick. The page walks through the routine and ends on what Muuka is not. A plain static site: no framework and no tracking.

Muuka product page: Every bill, marked as paid, with the App Store badge and Home on a phone

Feature cards: one bill in three fields, amounts that change, not this month, dark mode, two themes, 132 currencies and moving to a new phone

App Store screens of Muuka 1.0. Amounts are examples.

Let’s build the whole thing.

Contact me