CustomFields

TrelloExport supports the Trello Custom Fields Power-Up.

The Custom Fields Power-Up allows you to create additional fields for this board that you and your team can set on cards. For example, you might want to add a date field that can be used to store when work was started on a particular card. You can toggle whether these fields should show up on the front of cards providing more glanceable information.

If you check the 'Custom Fields' option, TrelloExport will add the custom fields available in current board to the Exported Columns dropdown, and then add such columns (and cards' data of course) to your Excel report, or to your HTML document.

Limits

Please be aware that exporting Custom Fields has some limits: if you choose the 'Multiple Boards' type of export, you will not get all Custom Fields exported, but only fields defined in current board.

That's because current implementation of TrelloExport loads custom fields before the export process is launched, to show field names in the “Export Columns” select box, and it will load fields from the current board only. Loading custom fields for all selected boards is certainly possible, but will require to re-engineer the process and I cannot tell when it will be available.

This said, if you're using the same Custom Fields in all of your boards, TrelloExport will export them nicely. If, on the other hand, you have different fields in the boards you wish to export, I'd recommend you to export boards separately.