custom-attribute-spec-summary

Custom attributes allow you to extend the data model with your own key-value data.

You can define up to 100 custom attributes in each group (shopper_attributes and admin_attributes). Both keys and values must be strings.

shopper_attributes are visible in shopper-facing catalogs and accessible to both shoppers and administrators. Ideal for customer-facing data, such as promotional labels or product tags.
admin_attributes are private and not visible in catalogs. Best suited for internal operational data, such as cost tracking or workflow metadata.