1. Go to Import/Export => Export
2. Under "Entity", pick "Products"
3. Select the fields you want to export. We recommend "SSIN" and "barcodes"
4. Press Export, go to "Reports" in the menu and wait for the export to finish
5. Download the export, open it in your favorite Spreadsheet editor.
6. You'll find a column called "barcodes.0". If the column is missing, you either forgot to pick it in step 3 or you don't have any products with barcodes yet.
7. Filter for empty values in the column barcodes.0
8. You now have a list of all products with missing barcodes.