Introducing ‘Mäuse’: An Expense Tracker for Couples
Mäuse is an expense tracker for couples that don’t have a shared bank account and therefore want to reconcile their expenses at the end of a month. It provides an extremely fast and seamless method to capture a cost right in the moment it occurs, either manually or by voice. Mäuse stores data locally on the phone (no cloud), is free without any ads or tracking, and allows exporting the expense data for further use. The code of the Mäuse iOS app is open source.
In other words: It’s the expense tracker I always wanted, couldn’t find anywhere, so I had to build it myself.
There are a million different apps out there to track expenses, but not a single one supported my unique requirements for keeping track of the various costs between me and my wife. We don’t have a system for who pays for what. It’s more or less random, a result of circumstance, who does the weekly grocery shopping, picks up the check at a restaurant, orders take-out, or charges the car on a road trip. We used to keep a note in our phone, manually entering what each of us paid for, and then settling the difference at the end of the month. It worked for years, but always felt like a waste of precious time.
Mäuse provides the simplest solution to this problem that I can think of: I press one button directly on the lock screen of my phone, say what I just paid for, and save. That’s it, and I can move on with life.
There are situations in which I can’t talk (or don’t want to), so I can also just type in the expense. By default, each new expense is split 50/50. If I want to split it differently, I just say it and Mäuse will track it accordingly. At the end of the month, I have a record of all the expenses, how I split them, and I can see at a glance what my wife owes me. She has the same on her phone, but from her perspective.
I could have made this more complicated, added much more sophisticated functionality. But it’s the restraint that makes Mäuse work. It does one thing, and it does it perfectly.
Tracking expenses via voice is possible thanks to GPT-Realtime-2, a speech-to-speech AI model from OpenAI. It has the ability to reason over what I say, which means: it’s smart. I can make it calculate things for me (“I just paid 15€ for coffee but it included a sandwich that was only for me. The sandwich was 7,99.”). I can also correct myself (“Add sushi for 38,75€, 60% is on me. No, actually make this 70%”). It can even deal with different currencies and will properly track it in Euro (“I just paid 450 Danish kroner in a restaurant”). All of that voice input is processed very fast, usually in less than a second.
Because I don’t want to add another subscription to your life, the voice mode in the Mäuse app works with your own OpenAI API key. You only pay for the actual API cost of the GPT-Realtime-2 model - I’m not involved at all in that, I make no money from it. In case you are wondering what it will cost you: For a typical month of my own usage of the voice mode in Mäuse, I pay between 10 and 20 cents.
Mäuse is available in the iOS App Store. The source code is on GitHub. If you want to make your own modified version of the app, or bring it to Android - go for it. Please share your feedback with me if you find the app useful (or not), and how it could be improved. You can reach me at support@mäuse.app.