← Back to work
Side project · Personal finance
Stacked – Personal Finance & Budgeting App
What I did: Designed and built a budgeting app that categorises transactions automatically and shows where the money goes.
Result: A working app used at home, with a public demo you can try.
Summary
- Personal finance tool designed around automation over manual budgeting.
- ML-assisted transaction categorisation for cleaner insights.
- System design built for open banking integrations.
Context & problem
Many budgeting tools assume users will manually maintain categories, envelopes and tags. Stacked flips this: it prioritises automation, low effort, and clear month-end insights.
Constraints
- Built to integrate cleanly with APIs like TrueLayer.
- Requires explainability for category/nudge decisions.
- Mobile-first design for daily use and weekly summaries.
Approach
User behaviour insights
Aimed at users who want clarity with minimal maintenance. No spreadsheets, no heavy UI.
System shaping
- API ingestion → cleansing → categorisation engine → insights layer → UI.
- Custom category rules + ML suggestions with confidence scores.
- “One-screen” summary with drilldown for anomalies.
Outcomes
- Clear product story and user value proposition.
- Scalable data model for real bank feeds.
- Foundation for shared budgeting and couple-mode.
Where this applies
Built for personal use, but the building blocks are common:
- Categorisation with confidence scores: expense management, accounting software, product tagging, support ticket routing
- Insight-first, low-maintenance UX: any product where users won't keep data up to date by hand
- Bank feed ingestion: lending and affordability checks, accounting integrations
Next steps
Next iterations: deeper ML clusters, shared spending flows, and explainable insights for end users.