Every trip I take with friends ends the same way: a tangle of "I got the taxi," "you covered dinner," "did anyone pay for the boat?" For years the answer to that mess was Splitwise. It was a genuinely good app. But somewhere along the way it filled up with ads, started gating basic features behind a subscription, and began nagging you to upgrade in the middle of working out who owed whom. A tool I used three weeks a year was suddenly asking for a yearly fee.
So before my last holiday I built my own. TripSplitter does exactly what I need and nothing I don't: log an expense, say who paid and who it was split between, and let it work out the balances. It handles multiple currencies with live exchange rates — essential when you are paying for some things in dollars and others in rupees — splits bills equally, by custom amounts, or by percentage, and then collapses everyone's debts into the smallest possible number of payments to settle up. No ads. No subscription. No upsell. Just the job, done.
The part worth dwelling on isn't the app. It's how little time it took. A few years ago, building even a simple multi-user, multi-currency expense tracker would have meant weeks of work or hiring someone. With AI in the loop, I described what I wanted, iterated on it conversationally, and had a working tool in an afternoon. The friction between "I wish something did this" and "I made something that does this" has almost vanished.
That shift matters beyond my holiday admin. A whole category of everyday software — the subscriptions that quietly add up to hundreds a year — exists because building the alternative used to be too hard for most people. That's changing. The barrier now isn't really coding; it's knowing what's possible and being willing to have a go. For people with a bit of that knowledge, AI is turning rented software back into something you can simply own. It is, quietly, a way to live a little cheaper.
I'm not pretending TripSplitter will dethrone anyone. It's a personal tool that happens to be useful to my friends too. But it solved my problem, it cost me nothing, and it's a small reminder that the tools we pay for are increasingly tools we could just build.