HouseMate Bill Tracker

The problem

BillSmart is a concept app for splitting shared household bills and automating payment reminders — designed to remove the social awkwardness of chasing housemates for money.

This case study focuses on one core flow: inputting a bill and automating reminders, seen through the lens of Sarah, a user who wants the app to do the "nagging" for her.

Competitive audit

I ran a competitive audit of Tricount, Splitwise, Settle Up, and Groupie (Tikkie). All four are polished and reputable — none are low quality — but they differ on positioning: Tricount for roommates and trip-splitting, Splitwise as the established default, Settle Up for users wanting more customisation.

Key weaknesses across competitors

Tricount lacks payment integration and instant settlements. Splitwise has monetisation creep and an increasingly cluttered UI. Settle Up lacks polish and item-level splitting.

The critical gap

None of the audited apps had strong native reminder systems, and none were built for cohabitation specifically — they're trip-splitting tools with household features bolted on as an afterthought.

Personas & problem statement

From the research, I defined four personas representing different money personalities within a shared house.

Sarah's problem statement

This case study focuses on Sarah: a busy, organised professional who needs a clear, unobtrusive way to get bills paid and ensure everyone contributes equally — because she doesn't like confrontation or negotiating over household expenses.

Product goal

Remind some users to budget, and reassure others the household's finances are on track, measured through app usage, reminders set, and whether the house stays on top of shared costs.

Finding the direction

The research gap — no competitor treats reminders as a core feature — shaped the direction entirely: rather than a splitting tool with reminders bolted on, BillSmart makes automated, non-confrontational reminders the centre of the experience.

For Sarah, this meant designing a flow where she could set expectations once (the bill, the split, the reminder schedule) and let the app take over the follow-up — rather than personally chasing anyone.

Sarah's user journey

Mapping the flow through Sarah's eyes: she recognises a need to track household spending, researches and downloads an app, registers via Google sign-in, and invites housemates via a shareable WhatsApp link.

She then inputs a bill and splits it — setting reminder dates at the same time, in the same flow. The app automatically nudges housemates who haven't paid or haven't logged an upcoming bill.

Key screens from the bill input and reminder setup flow.

Key decision: reminders come from the app, not from Sarah

The central design decision was framing reminders as coming from the app rather than from any individual housemate. Sarah sets it up once, then steps back — the app does the nagging, removing the social friction entirely.

Decisions & trade-offs

This was a design exercise without formal usability testing — so rather than reported results, here are the key decisions and trade-offs made along the way.

Results & next steps

This flow addresses Sarah's need directly — but the other personas point to a substantial amount of further work.

Next steps

Prototype flows for Maya, Marcus, and Ray, then test reminder tone and timing with real users — to see whether automation actually reduces the "nag" feeling, or just relocates it.