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- 02 Aug, 2025*
I started tracking my financial expenses to understand how much I spend and what I spend it on. My goal is to limit spending to two-thirds of my net income and save the remaining third.
To do this, I defined several spending categories that help me track expenses across all my different bank accounts.
The process starts by logging every transaction. I classify each one to determine whether it’s an actual expense (i.e., a debit transaction to a recipient that isn’t one of my own accounts). Then I specify whether the expense is shared, and if so, wha…
Johannes’ blog home about blog subscribe
- 02 Aug, 2025*
I started tracking my financial expenses to understand how much I spend and what I spend it on. My goal is to limit spending to two-thirds of my net income and save the remaining third.
To do this, I defined several spending categories that help me track expenses across all my different bank accounts.
The process starts by logging every transaction. I classify each one to determine whether it’s an actual expense (i.e., a debit transaction to a recipient that isn’t one of my own accounts). Then I specify whether the expense is shared, and if so, what percentage I paid. For shared expenses, I assume I either received a refund or that the transaction is tracked in an app like Splitwise.
In the past, I struggled to maintain this habit because the process was cumbersome—it required downloading bank statements and doing the math manually. Now, with ChatGPT and the OpenAI API, I can send full PDFs of bank statements and receive structured data in return. Using Replit, I built a wrapper around the API that lets me automatically send any statement to the app. ChatGPT parses and classifies the transactions, and I just double-check and approve the results. The final output is a CSV of all transactions.
It works extremely well and has helped me gain a clearer understanding of my spending patterns.