Barcodes are one of those things nobody thinks about until a listing gets blocked. I ran into it when I brought a two-pack of toothpaste tube squeezers from Amazon onto Walmart. On Amazon the product existed as an ASIN with no UPC. On Walmart, that wasn't going to fly. The fix ended up being simple, but getting there took three tries.
GTIN, UPC, EAN, ASIN: what's what
- GTIN (Global Trade Item Number) is the umbrella term for product identifier numbers.
- UPC is the 12-digit GTIN used on most products in the US.
- EAN is the 13-digit version used in much of the rest of the world.
- ASIN is Amazon's own internal product ID. It only exists on Amazon. Other marketplaces can't use it.
Amazon and Walmart both want a GTIN for each product so they can match listings to the right item. If you don't have one, you either get one or apply for an exemption.
Getting real barcodes
GS1 US is the organization that issues UPCs in the US. You can buy a single GTIN for one product, or license a company prefix if you'll have many products. Codes bought from GS1 are registered to your company, which is what Amazon and Walmart check against.
Cheap UPCs from resale websites are tempting, but they're often from old prefixes registered to some other company. When a marketplace looks up the code, it doesn't match your brand. Some sellers get away with it, and some have listings suppressed months later. If you plan to build a brand, buy from GS1.
Each variation needs its own GTIN. A 2-pack and a 4-pack are different products, and so is each color or size you sell as a separate option.
When an exemption makes sense
An exemption lets you list without a GTIN. It's meant for products that genuinely don't have one: private label goods you haven't barcoded, handmade items, bundles you assemble, and some generic parts and accessories. Both marketplaces want evidence, usually photos of the product and packaging from every side showing there's no barcode.
On Amazon: "Generic" worked
On Amazon, unbranded products can often be listed with the brand "Generic" under a GTIN exemption. That's how my tube squeezer listing ended up. At one point there was a brand name issue on the listing, and Amazon Seller Support set the brand to "Generic" to resolve it.
The catch with "Generic" on Amazon is that you don't get brand protections or Brand Registry tools, and anyone can sell on a generic listing. If you plan to build the product into a brand, getting a trademark and listing under your brand is the stronger long-term move.
On Walmart: "Generic" got rejected
When I imported my catalog to Walmart, the tube squeezers came over with no UPC. Here's what happened, in order:
- I tried setting the product ID type to CUSTOM with the brand "Generic." Walmart returned a data error saying the brand or product type wasn't eligible for an exemption, or that the exemption was denied.
- I submitted a request through Walmart's GTIN Exemptions page in Seller Center, still under "Generic." Same rejection. I confirmed my account had admin permissions, so that wasn't the problem.
- I resubmitted under my actual brand, ML Necessities. Walmart's product identifier rules discourage placeholder or unrelated brand names, and "Generic" is exactly that. The exemption was approved.
So the same product, with the same brand field, was handled in opposite ways by the two marketplaces. Amazon was fine with "Generic." Walmart wanted a real brand. If you sell on both, put your real brand on the Walmart request from the start.
Look for the GTIN exemption request in the catalog or item settings area of Seller Center, not under account settings. Use your real brand name, pick the most accurate category, and upload clear photos showing all sides of the product and packaging without a barcode. If you get rejected, read the reason carefully and fix that one thing before resubmitting. Emailing seller help can also get you more detail than the automated rejection message.
Choosing between a GTIN and an exemption
| Situation | Best option |
|---|---|
| Reselling a branded product made by someone else | Use the manufacturer's existing UPC |
| Private label you plan to grow into a brand | Buy GTINs from GS1 US |
| One-off test of an unbranded product | Exemption may be quicker |
| Bundles and multi-packs you assemble | Your own GTIN per bundle, or an exemption if eligible |
| Handmade goods | Exemption |
Barcodes inside the warehouse
Don't confuse a GTIN with the label that goes on each unit for FBA or WFS. Amazon uses its own FNSKU labels to track your specific units, and Walmart has its own requirements for scannable barcodes on inbound items. An exempt product still needs a scannable label on every unit before it goes into a fulfillment center. Check the inbound requirements in my first WFS shipment before you pack anything.
Questions people ask
What is a GTIN?
A Global Trade Item Number is the number behind a product barcode. In the US the most common is the 12-digit UPC. Marketplaces use it to identify exactly which product a listing is for.
Can I buy cheap UPC codes online?
You can, but it's risky. Amazon and Walmart check barcodes against the GS1 database, and codes resold from old prefixes often show a different company as the owner. That can get listings blocked or removed. Buying directly from GS1 US is the safe route.
When can I get a GTIN exemption?
Usually when the product genuinely has no barcode: private label items without one yet, handmade goods, bundles, and some parts and accessories. You apply per brand and category, and the marketplace may ask for product photos showing there's no barcode on the item or packaging.
Why did Walmart reject my GTIN exemption?
Common reasons are a placeholder or unrelated brand name like 'Generic,' a category that isn't eligible, or images that don't clearly show the product and packaging. In my case, switching the brand from 'Generic' to my real brand name got it approved.