It relies upon 2 custom data files:
"Transactions" requires having an (at least a free) account with the money-management site Mint. Using their site (or app), a user can download this file to get a current record of their entire banking transaction history. (To download your own, login to their site, hit "transactions" tab - top of page, and then click on the "Export all Transactions" button - bottom-right of page). While currently acquring this file from Mint is a manual process (primarily due to security concerns), subsequent app versions may attempt to automate this process.
"Billers" is a "manually-editted" list of vendor nick-names (e.g. "BOA" vs. "Bank of America, LLC).