Meus Gastos

The problem

Every month a chunk of money disappears and you cannot say where it went. Not because the information is unavailable — bank apps have all of it — but because it arrives as a statement, which is a record, not an answer.

The tools meant to fix this mostly fail on the same step. Logging a coffee takes six taps and a category picker with forty options, so you stop logging coffees, and a spending tracker with gaps in it is worse than none.

What I built

An expense tracker where the entry path is the whole product. Amount, category, done — about five seconds. Everything else in the app is built on the assumption that the log is complete, which is only true if logging never feels like work.

On top of that: charts that show where the month actually went, and spending limits per category that tell you before you blow through one rather than after.

It runs as an Android app and in the browser, sharing one account and one dataset. Sign in with Google on either and the same data is there.

Technical decisions

Expo and React Native, not native Android. One TypeScript codebase produces the Android app and shares its data layer with the web build. For a solo project the deciding factor is how much surface area I have to maintain, and this cut it roughly in half.

Supabase for auth and data. Postgres with row-level security means a user’s rows are isolated by a policy in the database rather than by discipline in the application. Google OAuth came with it, and Google sign-in is the difference between a signup form and no signup form.

Categories are icons, not a dropdown. A grid of icons is one tap and no reading. A <select> with forty entries is the reason people abandon expense trackers in week two.

Separate web app rather than a responsive shell. The Next.js web build is its own project against the same Supabase instance. Phone and desktop are genuinely different sessions — the phone captures, the desktop reviews — and pretending otherwise makes both worse.

Where it stands

Live and free at meusgastos.dev.br, on Google Play and in the browser.