I was seriously considering using Plaid API[1] to build an app that would download my transactions automatically, categorise it, and prompt me to only verify entries it classified with low-confidence. But, Plaid API at the time did not support all my bank accounts, which made the effort moot.
Another concern of mine is exporting such personal data to a 3rd party. Ideally, an open source tool that strictly runs on my laptop would be the best!
[1] - https://plaid.com