I make about $7000 a month with a web app that extracts transaction data from PDF bank statements.
I built it because my bank only provides PDF statements and I wanted to analyse my spending over the last few years. I wrote some Kotlin code to work with the PDFs, found it incredibly difficult to implement so I figured other people would have this problem and turned it into a web app.
Wow, I've been doing this for nearly 10 years with multiple banks and auto-mergjng the output into my accounts, as well as to update memberships of an organisation using membership fee transactions from those files.
It never occurred to me to think of offering it to others through a front end, or that there's a side income's worth of interest in that kind of bank PDF scraping.
A fun thing I discovered doing this was when my software reported some mismatch errors when I merged in a bank-generated PDF for a date range partly overlappong what I'd already loaded. Turns out the bank PDFs were missing a random subset of transactions over a large date range - as was the online banking transaction history! This went on for a few months until the bank fixed their systems.
I started off by buying Google Ads, but I lost money running them. Eventually I stopped running the ads and focused on writing blog posts. Also I think the domain sort of helps.
Question for ya if you don't mind: I had to do some PDF scraping a while back as part of a side project collecting alternative social/economic datasources.
Even within a single site, there were often errors at the fringes, especially if things like layout/styling changed, and my concern about giving bad data to users (or needing to constantly be checking data quality and adjusting custom parameters for each target site) held me back from ever feeling confident enough to convert it into a paid product.
I don't mean for you to give up your secret sauce here, but wondering if you ran into this same issue, and what your approach was from a business/customer expectations perspective?
Oh yes I ran into this issue many many times. The way I dealt with it is a bit insane. I classify bank statements using images or text on the first page. Then I run custom code for that document type.
I also have a "pretty good" fallback algorithm if the statement cannot be classified.
Usually banks have a template so the edge cases aren't so edgy. Had to do this with Canadian banks and each one had their own template, but once you parsed it, generally, it worked until they updated their template again.
I built it because my bank only provides PDF statements and I wanted to analyse my spending over the last few years. I wrote some Kotlin code to work with the PDFs, found it incredibly difficult to implement so I figured other people would have this problem and turned it into a web app.