Let's start with a bit of background - GTINs are unique and globally recognizable item identifiers developed by GS1 (gs1.org) allowing comparison engines, stores, and barcode scanners (to name just a few) to identify items and group sellers selling the same items together.
GTINs provide their own 14 digits format and are also acting as an umbrella/unifying format spanning across various already preexisting barcode standards such as EAN in Europe, UPC in the United States or JAN for Japan, and more e.g. ISBN for books, etc.
GTINs / barcodes are widely used with barcode scanners as well as price comparison engines due to their unique quantities allowing them to group items together or have a safe and stable unique and global item reference as mentioned above.
Now what to do if they are missing in your store and you get the warning inside Google Merchant Centre diagnostics report? - here are some solutions that hopefully might allow you to source them and add them to the Google merchant center feed:
- Probably the most obvious but not always a quick solution is to type them down from product boxes - they should be featured around the barcode label area.
- In case you don’t stock your items or the scale of how many you have is too big to do it box by box throughout your inventory, the 2nd option would be to check with your suppliers. As GTIN is a global standard and widely used across the industry for years, your suppliers most likely have them and hopefully can provide them to you in a way helping to assign them to your items - you can easily add them under our platform if you have them in some spreadsheet format.
- Buy them - if you are a manufacturer yourself and items you list in the Google merchant center are showing a missing GTIN warning, that means Google thinks you should have it and as such you might need to buy them from GS1. However, if you are not a manufacturer, buying unassigned GS1 barcodes and assigning them to branded items might be risky as Google often knows the ranges that a brand purchased and can asses yours against them.
- Probably the quickest way but also it’s the last on the list as it's not really a solution - if you can’t use any of the steps above - just ignore the warning, it's not a blocker, your items are active and we are not really sure how big an impact it has on the performance since when you think about it, actual google shopping ads (not listings) are not grouped with each other anyway. And yes, it might give Google some extra signals but it's not like most aren’t already there - title, brand, MPN, etc. However please note, this is only if you can't get the real barcodes or it is a very long and time-consuming process that will take ages.
But why Google doesn’t require it across all my items? - that is because although you can buy them from GS1, GS1 doesn’t have a database that clearly assigns a barcode to an item, the assignment is usually managed under each of the manufacturer databases so Google assumes those things based on how many sellers sell given brand, or what category you list under and how often GTIN is being pushed there by others. Sometimes brands provide Google with barcode ranges using Google Manufacturer Centre or other means Google provides them with for that.
OK, but someone told me about using identifier_exists google shopping feed attribute as a possible alternative - Well, you could remove the missing GTIN warning by using identifier_exists = no however only if you would also remove brand and MPN attributes from the feed alongside, meaning - compromise feed over a warning which doesn’t really block your items anyway.
Can I make my own? - Nope, you can have lots of issues by making up yours since GTIN has a self-validation mechanism that Google checks, and in case it doesn’t pass, it won’t be a warning but straight disapproval so it best not to send one and then send an invalid one, and even if you could somehow make it valid by guessing it, you might end up merging your items with completely different ones due to GTIN collisions.