I recently posted my Net Worth sheet and commented that I had abandoned the project in favor of a web-based front end. I found services like Mint and Personal Capital useful in the past, but was frustrated by a) lack of customization b) loss of control of my financial data c) risk of the service changing or closing. This is part of what prompted me to subscribe to Tiller a few years ago.
Over the course of a year I built out my sheets, supplemented them with user-developed and custom-built add-ons, but was frustrated that there were no good mobile views and that web-hosted spreadsheets are simply not a good way to visualize and interact with data. I was also frustrated by the possibly of data corruption: I did not want to routinely be in my transactions and balance history sheets where the possibility of an errant key stroke could disrupt alot of data.
About 6 months ago I began experimenting with AI with a Claude Pro subscription. I have some experience with coding, but no experience with web development. Using some simple prompts, I began to build a web interface that used Tiller Foundations as a data repository for a comprehensive personal financial dashboard. Over a few months, I build out net worth, debt tracking, investment returns, asset allocation, rebalancing, budgeting, a YNAB or Actual Budget style envelope budgeting system, Monte Carlo and Tax projections.
These are all in a web interface with desktop and mobile views. Anything related to transactions and balances come straight from the foundations sheet. Investment holdings are generated from a separate tab that I maintain. I have heard rumors of an investment holdings beta from tiller, but I’ve not been invited to participate. I have been able to update my holdings tab automatically using a googleapps script through SimpleFin Bridge ($15 a year).
At this point I rarely have a need to go into my spreadsheets directly.
I maintain the code in a private repository and accessed through a domain secured via cloudflare with google authentication. At different times the project has used the google sheets API or the "Google Picker’ service to access data from my sheets. I’ve given the project write access but the interface only supports writing to the category column of the transactions sheet.
There is also a Json file that is housed on my google drive that holds inputs that i’ve put into the app that I want to persist but don’t belong in my sheets.
I built this entirely using claude. I’ve used mostly sonnet and opus models. I’ve not given claude or any other AI direct access to my sheets. Instead I’ve described a sheet or used cut and paste functions for row and column headers. I’ve also been able to describe sheets to claude using language like “reference the standard balance history sheet from tiller.” This project references the transactions, balance history, accounts, and categories tabs. It also references my own holdings tab which is housed in a separate sheet.
I’ve also done periodic security audits and set up restrictive access policies in cloudflare.
I do not intend to share access to the code or support multiple users. Its nothing special, claude did all of it. It works really well for me, but I just don’t feel comfortable taking responsibility for anyone else’s data. But maybe you will get ideas for how you can build something for yourself.
I’ve attached some screenshots with test data. Many of these graphics are interactive with hover logic and drill-downs for asset allocation and budgeting.
