QFX is built on OFX
OFX (Open Financial Exchange) is a general-purpose interchange format for bank and credit-card data, used by many financial institutions and personal finance tools. QFX is Quicken's variant of it — a Web Connect file that uses the same OFX structure and tags, distributed by banks specifically for importing into Quicken.
In practice, a QFX file is an OFX file in almost every technical respect: the same header format, the same transaction blocks, the same fields for dates, amounts and payees. The differences are more about labeling and intended destination than about the underlying data structure.
Why they can look identical
Because QFX doesn't meaningfully change the OFX structure, a parser reading the raw content often can't tell the two apart from the file alone — there's no unambiguous marker inside the file that says “this is QFX, not OFX.” Some banks even distribute what is essentially the same export under both extensions, depending on which product the user says they want to import into.
This is also true of QBO, the QuickBooks-associated variant of the same OFX family. All three — OFX, QFX and QBO — share enough structure that software has to rely on context, not just file content, to label them correctly.
Typical use
OFX exports are the general case, used across many banking and finance apps. QFX is specifically the label banks use when the download is meant for Quicken, and QBO when it's meant for QuickBooks. None of the three require the associated desktop software to read — they're all just structured statement data.
How Bankfile handles the OFX family
Because the three formats can be structurally identical, Bankfile detects an OFX-family file and asks you to confirm whether it's OFX, QFX or QBO before finishing the conversion, so the export is labeled correctly. After that, conversion works the same way for all three: transactions are read locally in your browser and turned into a CSV or Excel file.