Timmy

Splitting expenses with friends shouldn't require a spreadsheet and a group chat argument. Every trip, every shared apartment, every dinner ends the same way — someone tracks it in Notes, numbers get fuzzy, and someone gets shorted. Timmy exists to kill that problem.

What It Does

Timmy handles both personal expense tracking and group splitting in one app. You can log your own daily expenses with categories, or create a group — a trip, a flat, a project — add people, and record shared costs. The app automatically calculates who owes whom and by how much, handling uneven splits and multiple currencies without manual math.

How It's Built

The entire backend runs on Firebase — Firestore for real-time data sync across devices, Firebase Functions for server-side balance calculations and settlement logic, and Firebase Auth with Google and Apple sign-in for frictionless onboarding. I integrated Firebase AI to help categorize expenses and surface spending insights automatically. Going serverless with Firebase meant I could focus entirely on the product experience instead of managing infrastructure.

The Flutter frontend is shared across iOS and Android. The UI prioritizes clarity — at a glance, you see exactly what you owe, what's owed to you, and how to settle up. No ambiguity.

Why I Built It

After building WhereDidISpend for individual tracking, the natural next step was group expenses — a harder problem because of multi-user consistency, real-time sync, and the combinatorial complexity of settlements across multiple people. This project pushed me deeper into Firebase's real-time capabilities and serverless function design.

Available on the App Store and Google Play.