Wumbi

Product and design

• I gave myself one rule. Logging an expense should take about three seconds, from opening the app to the moment it is saved.
• The whole app is five screens. Choosing a wallet, a currency, a date or a repeat happens in a bottom sheet, so you never wander off somewhere and lose your place.
• There are no categories at all. You write #coffee or #trip in the description and the tag exists from that moment.
• I designed the screens and the design system myself, and gave the app a small mascot who peeks in from the edge of the screen. You can hide him in the settings if he gets on your nerves.

The app

• Flutter with Riverpod and hooks, auto_route for navigation, and every feature split into its own data and UI layers.
• Your data lives in an SQLCipher database on the phone, encrypted with AES-256, with the key kept in secure storage. The free version needs no account and no server.
• A custom numpad that gives haptic feedback the moment your finger touches a key. Income and Expense save in one tap, the fields clear, and the screen stays open for the next one.
• 64 currencies including Bitcoin, Ethereum and USDT with 8 decimals. Each wallet has its own currency and the total is converted into the one you think in.
• Repeating payments become subscriptions you can pause or stop, and when you open the app after a few days it catches up on everything that was due.
• A tag map where each tag is a bubble sized by the money that went through it, plus charts for income, expense and spending by tag.
• Seven languages, Arabic included with a full right to left layout.

The website

• I built wumbi.app as a static site in the same seven languages. The phone mockups on the page are interactive and use the real labels from the app, and there is a waitlist for launch day and a free budget planner template that brings people in from search.

• Money that stays true. You can type an amount in euros and pay from a dollar wallet. I store both numbers and the rate of that day, so last month never changes when the rates move. Rates are cached for 12 hours, so the app works fine on a plane.
• Three seconds is harder than it sounds. I had to count every tap. The Save button went, the confirmation screen went, the category picker went.
• Free today, sync tomorrow. The database already uses UUIDs, soft deletes and timestamps, so backup and bank sync can arrive with premium without rewriting the data layer.

The first version of the app is built and the website is live with a waitlist. I am polishing the last details before the release on the App Store and Google Play. It is also the clearest picture of how I like to work, one person carrying a product from the first sketch to the store listing.