Honestly the hardest part was normalizing the date and amount formats across banks. Each one exports slightly differently. I wrote a small Python script per bank that maps their CSV columns to a common schema (date, description, amount, category) and then bulk-inserts into SQLite. Once you have the schema figured out it takes maybe 20 minutes per bank. The manual step is downloading the CSV each month, but most banks let you set a date range so it is just a few clicks.