Apps for Shared-Flat Expenses: Three Real Options

The flat of four and the app that holds up

I have lived in shared flats for eight years, and in that time I have watched expense-splitting apps come and go the way flatmates have: with high expectations, honeymoon periods and eventual break-ups. I have tried the three options mentioned in any conversation on the subject today: Splitwise, Tricount and, more recently, ControlarGastos. And the conclusion I have reached, after a full year of intensive use in a four-person flat with tenant turnover, is that none of them is perfect and that the differences matter more in daily life than they seem from the outside.

This is not a marketing comparison. I am not going to tell you which is best in the abstract, because that depends on what kind of flat you have, how many of you there are, how much mental maturity you have to absorb friction, and whether people come and go every six months or you are the same crowd as ever. What I will do is put numbers, scenarios and names to the points where each one breaks.

Why a flat of four is where things get complicated

A couple needs little more than a notebook. Three flatmates manage with a spreadsheet. Four starts to become unmanageable, and from five on it overflows. The reason is mathematical: the number of bilateral relationships in a group grows with the square of the number of members. In a group of two there is one relationship. In a group of four there are six. In a group of six, fifteen. Each relationship is a possible debt in one direction or the other, and tracking that by hand is exactly the kind of task apps exist for.

On top of this comes turnover. A flat of students or young professionals is not stable. Every year tenants move in or out, and the operational problem is: when someone leaves, does the app let you settle accounts with that person and keep running with those who stay, without losing the history? When someone new arrives, do they inherit a clean zero balance, or do they have to take on a tangled situation? These two questions, the one about leaving and the one about joining, are what break the apps that seem to work fine in the first few weeks.

The three options I tried for real

1. Splitwise

The most popular, the oldest, the one everyone recommends on Reddit. It has a very decent free tier and a premium version that adds CSV export, automatic reminders, receipt scanning and detailed categorisation. The interface is clean and the flow for adding an expense is quick: you tap the button, enter the amount, choose who it's split among and done. It has the advantage of the network effect: if your former flatmate already had it, there's no need to convince them to install anything new when they join the flat.

The ugly part appears when the flat is one of four and you start using it for real. The free version has been trimming features over the years, and since 2023 there is a daily limit on the number of expenses you can enter without paying. If you add lots of small movements (a fruit purchase, a coffee, the bread), you hit the wall and it pushes you towards the subscription. Serious export is behind the paywall, and so are the automatic reminders. Currency handling is decent but not excellent. And tenant turnover is manageable, but not smooth: you have to do a final balance, move that person out of the group and start practically from scratch with the new one.

2. Tricount

The European option, founded in Belgium and acquired a few years ago by a banking group. It is the favourite of people who travel in groups, because its flow for creating a group, adding people and recording expenses is probably the most intuitive of the three. It works very well without forcing every member to have an account: one person can keep the books and the rest simply receive the summary at the end.

That same virtue is its biggest flaw when we talk about a permanent flat. Tricount is designed for ephemeral groups: the trip, the birthday, the work dinner. When the flat has been running for eight months, you have 320 movements in the group and the interface starts to feel dense. Search isn't agile, filters are limited and category management is basic. For a long-term shared flat it falls short. And the monetisation model through banners, though discreet, is a constant reminder that the product isn't meant to be your daily financial companion.

3. ControlarGastos

The most recent of the trio and the only one built with the Spanish market in mind, with everything that implies: VAT treatment in some categories, natural integration with the local working calendar (the difference between a weekend and a long bank-holiday weekend matters) and, above all, a product decision that shows in a shared flat: splitting to the cent. It distributes the cents by largest remainder, not by truncation, so nobody always pays the rounding. It sounds trivial. After a year in the flat, it isn't.

The strong part is the flexibility of the splits. It lets you define categories with different percentages per person (the washing machine is split equally but the internet bill is paid slightly less by one because they work remotely and the others agree to absorb a bit more to have double the contracted bandwidth). It allows subgroup expenses (the three of us who go to the gym share a family account, the fourth one isn't in it). It allows partial settlements: when someone leaves, a balance is drawn up in their name, transferred, and they leave the group without touching the history. That last part is what really changes things in a flat with turnover.

The weak part, in honesty: it is more recent, so the user base is smaller and the network effect is weaker. If your flatmate arrives at the flat already with Splitwise installed and twenty old groups in their account, convincing them to switch is real friction. And the free version has a monthly expense limit that, for a very active flat, falls short.

What no comparison tells you

The real difference between the three isn't in the features. It is in how each one handles asymmetry. A real flat is not four people consuming the same. It is four people with different schedules, different budgets, different habits. One buys the good olive oil and the rest buy the generic one. One makes coffee for everyone. One goes off to their parents' place for two weeks and consumes nothing. If the app forces you to push everything into equal shares, the app is lying. And the app's lie turns into small resentments that end in real arguments.

In my judgement, all three hold up a flat of two or three people. The fourth variable is where they part ways. If there are four or more of you and you are going to be together at least a year, you want a tool that treats asymmetry as the norm, not the exception. Any decent system should allow what I have already described: percentages per category, subgroups, partial settlements and a fair split to the cent. And it should do so without the flow of adding a coffee costing more time than the coffee itself.

Conclusion: the right app is the one that survives year two

Any app is good the first month. You enjoy using it, you record everything, there is a touch of play in watching the balances settle. The interesting question is what happens with the tool in month seventeen, when the flat has already had two tenant changes, a boiler breakdown, a month-long bin strike and a crisis over an electricity bill that doubled the previous year's. The app you keep opening then is the good one. The others stay on the phone screen untouched, while you go back to the spreadsheet or, worse, to the notebook.