Most Catalog Partners require eligible UPCs in order for your products to be listed on their site. Before Catalog will push your products, every variant must include either a GS1-compliant 12-digit UPC or 13-digit EAN. If UPCs are missing or non-compliant, Catalog will block these products from being approved for Partners to sell them.
Before submitting your items, you can validate your barcodes through:
https://www.gs1us.org/tools/gs1-company-database-gepir
*Catalog validates barcodes based on the GS1 checksum standard