I built an expense tracker where the primary input is voice. The thesis: expense tracking apps fail because manual entry has too much friction, which is why most people abandon them within weeks.

How it works: - Open app, tap mic - Say "yesterday I spent 30 dollars on lunch at Chipotle" - AI extracts: amount, merchant, category, date - One tap to confirm and save

Other features: - Receipt scanning with ML Kit OCR + Gemini Vision for parsing - Background notification listener that catches bank alerts and creates pending entries - GPS-based currency detection for travelers - Multi-language with native script fonts (Nastaliq for Urdu, Devanagari for Hindi, Amiri for Arabic) - Offline-first with Google Drive sync

Tech: Flutter, Riverpod, Hive, Gemini 2.0 Flash

The hardest part was prompt engineering for consistent JSON output across languages. Had to build "Supreme Laws" into the system prompt - things like "never translate native text" and "extract currency from context."

Free tier available. First 500 users get Pro free for a year.

Play Store: AuraSpend

Happy to discuss architecture, prompt engineering approach, or take technical feedback.