Misfit tooling
Spreadsheets and paper notebooks cannot compute automatic splits or track payer accountability in real time (44.4% and 66.7% usage).
Mobile App / Fintech / UFRN Research
From spreadsheets to software: turning shared financial friction into a system of trust.
A collaborative mobile platform designed to eliminate social awkwardness around shared money through automated balances, transparency, and frictionless pairing.
- Role
- Product Designer
- Context
- Combim (UFRN Research)
- Timeline
- Jul 2025 – Present
- Squad
- PM & Product Designers
Context
Couples and families sharing living expenses frequently depend on spreadsheets and physical notebooks — tools never engineered for this dynamic. They fail to compute proportional splits, do not track who paid what, and cannot manage recurring expenses.
Through empathy mapping and participatory research, we discovered that the real issue was not just organization, but the emotional friction and hesitation around settling debts.
66.7%
rely on notebooks or spreadsheets to track shared costs
60.0%
have partial or zero clarity on individual vs. joint expenses
77.7%
experience recurring awkwardness chasing split payments
0
calculations needed to understand an account balance
Problem
Lack of transparency
The majority of cohabitating pairs lack a clear distinction between what constitutes individual versus joint household expenses (60.0%).
Social friction over trust
Chasing or being reminded about split money is an uncomfortable, repetitive chore (77.7%) — the core issue is interpersonal trust, not just bookkeeping.
Flow 01
Dual-branch entry & debt settlement
A unified creation trigger branching into either a multi-step shared expense setup or a one-tap debt payoff.
Branch A
Debt Settlement (Quitar Dívida)
A direct path designed for speed. Automatically calculates pending balances between users and registers repayments without forcing extra form fields.
Branch B
Shared Expense (Adicionar Despesa)
A structured 2-step wizard separating financial parameters (category, installments, payer) from final split confirmation to prevent input fatigue.
Flow 02
Expense logging & transaction management
From first entry to granular editing, streamlining how users record, review, and adjust shared costs.
01
Empty State
A clean onboarding view encouraging first-time logging with clear guidance.
02
Expense Ledger
A unified timeline tracking recurring items, individual shares, and quick deletion actions.
03
Expense Details & Edit
Intuitive modal to configure payer distribution, category tags, and split ratios.
Authentication & Setup
Two-sided account pairing without fragmented invites.
Traditional shared budget apps drop users directly into complex balance grids or force asynchronous invitation links that cause heavy drop-off before the first transaction is logged. Combim replaces this friction with an immediate, self-contained onboarding flow: one user authenticates and seamlessly personalizes profiles and avatars for both members in under 60 seconds.
01. Auth Modality
Frictionless Social & Magic Auth
Integrated Google Social Sign-In and fast email authentication to bypass password fatigue and minimize the time-to-first-screen.
02. Dual-Identity Setup
Inline Profile Provisioning
Allows the primary user to define names and expressive 3D avatars for both parties upfront, instantly preparing the ledger for two-way settlement.
03. State & Backend
Relational Household Pairing
Instantiates a unified shared household schema upon completion, ensuring all subsequent split entries link to their persistent profile tokens.
Results & Status
Live testing with real households is currently awaiting final clearance from UFRN's ethics review board. Validation to date has centered on technical delivery and rigorous process governance:
Technical Delivery
7 Native Navigable Flows
Fully functional on physical devices with React Native, Expo, and TypeScript. Supported by a 32-token architecture (16 color, 8 typography, 8 spacing) synced between Figma and code.
Process Rigor
3-Tier Review Cycle
Iterative reviews moving from peer Product Designer alignment to PM discovery reviews, concluding with PM validation directly in the codebase.