ProperSoft converters convert from many formats with transactions:
Import into QuickBooks 2018-2021 and Quickbooks Online through the QBO format (use Transactions) for the IIF format (all QuickBooks Desktop versions are supported). For general journal entries, convert to QBJ or IIF format with CSV2QBJ.
Import into Quicken 2005-2021 as QIF format and Quicken 2018-2021 as QFX (Web Connect). Keep using your Quicken version by converting to QIF format.
Many cloud apps import directly from bank accounts, but not every bank. Your client may not have direct import feature. Use the converter and make your file importable. Most of accounting and personal finance cloud apps import OFX. Some imports CSV as well. See below or check the cloud app you use which format they prefer to import.