This is the project I teased at the end of the last post. It started with a problem we probably share with a lot of couples.
The problem
My girlfriend and I each have our own bank accounts and credit cards. We split shared expenses — groceries, restaurants, travel — but personal spending stays personal. Her shoes are on her. My whatever-I-buy is on me.
At the end of every month, we’d sit down and go through every transaction across all our cards. Is this shared or personal? Who paid for what? Then we’d manually categorize everything in a Google Sheet, tally it all up, and whoever spent more on shared expenses would get paid back by the other.
It worked. But I dreaded it every single month. Too many transactions, too much back-and-forth, too much manual work for something that felt like it should just… happen automatically.
Projet 4C
4C stands for Couples Credit Card Conciliation — which sounds more serious than it is.
The idea is simple: instead of manually going through everything, we upload the CSV export from each of our cards once a month. The tool handles the rest — categorizing transactions, splitting shared vs. personal, tallying who owes who, and displaying everything in a clean dashboard with spending by category and month over month.
I did a quick search before building it. Nothing out there checked all the boxes. Most tools are either too complex, require linking your bank accounts directly, or aren’t free. I wanted something lightweight, private, and completely free.
But honestly? Even if something existed, the fun part was building it myself — again with Claude.
What’s next
The next post will be a preview of the tool as it stands today. Stay tuned.