To sell on Amazon, products need to be identified in your Shopify catalog to be listed on Amazon.  Once identified Amazon applies a special code called an ASIN to the products.

ASINs

An ASIN (Amazon Standard Identification Numbers) is Amazon's unique number for a product being sold on Amazon. ASINs are unique blocks of 10 letters and/or numbers. 

You will find an item's ASIN on the product detail page alongside further details relating to the item.

For example, the ASIN for Hasbro's "Monopoly" game is B00005N5PF.

If you already know the ASIN for a product you are selling you can simply use that. If you don't know it, Amazon uses your GTIN to try and find the ASIN or creates a new ASIN for you.

What is a GTIN? 

A Global Trade Item Number (GTIN) is a unique identifier for trade items, developed by GS1 - “GS1 defines trade items as products or services that are priced, ordered or invoiced at any point in the supply chain”. Such identifiers usually come in the form of:

12 digit Universal Product Code (UPC)

13 digit European Article Number (EAN)

13 digit International Standard Book Number (ISBN).

Your product GTIN is represented by the product’s barcode and associated barcode number.

Without a GTIN/product identifier on Amazon, you will not be able to list your products unless you successfully apply for a GTIN exemption.

3 common methods for identifying your product GTIN:

1. Check the product’s barcode
2. Request the GTIN from your supplier
3. Use a barcode lookup website to search for the product

*BE CAREFUL* Avoid purchasing “recycled” codes that are re-sold by online suppliers. Recycled codes can cause complications for your business down the line and often do not justify the upfront savings.

Purchasing GTINs with GS1

It is important to always purchase your GTINs from a reputable source, we recommend purchasing directly from GS1. To get barcodes for your business you’ll first need to join GS1. By becoming a member you obtain the licence for a unique range of barcode numbers. You also gain access to support, training and more.

Adding GTINs to your product catalogue

When adding your GTINs to your product catalogue, it is important that you upload your codes to Shopify into the 'barcode' field.  This ensures Shopify continues to be the ‘source of truth’ of your product data.

Whilst, it's possible to enter them directly in Amazon by Codisto it's not advised due to breaking the 'source of truth' away from Shopify.  You're having to input them anyway, you may as well input into Shopify which allows them to be used on your webstore as well.  Plus Shopify has great importing capability from a csv file which is better than manually inputting one by one.

Consult Shopify help guides for more information on editing your products.

UPCs

Universal Product Code (UPC) is (generally) a 12-digit bar code used extensively for retail packaging in United States. (They are sometimes represented as 13 digit codes by adding a leading 0 to make them compatible with EAN’s - see below)

The European Article Number (EAN) is a barcode standard either 8 or 13 digits - never 12.  Each EAN uniquely identifies the product, manufacturer, and its attributes; typically, the EAN is printed on a product label or packaging as a bar code. We require EAN codes to improve quality of search results and the quality of the catalog as a whole. You can obtain EANs from the manufacturer. If your products do not have manufacturer EANs, and you need to buy EAN codes, you; should go directly to GS1 UK http://www.gs1uk.org

For example, the EAN of  "Colgate Total 75 ml" is 4011200296908

The International Standard Book Number (ISBN) is a unique commercial book identifier barcode. Each ISBN code identifies uniquely a book. ISBN’s are either 10 digits long or 13 digits long and start with 978 or 979 (i.e. you can convert a 10 digit ISBN to an 13 digit one by adding 978 to the front). All ISBN assigned after 1 Jan 2007 have 13 digits. Typically, the ISBN is printed on the back cover of the book.

 

For example, the ISBN code for J.K.Rowling's "Harry Potter and the Deathly Hallows", Adult Edition, Paperback, UK edition is 978-0747595823, and this code identifies uniquely this book and edition.