More sellers than you would guess don't know what to enter in the "barcode" field on Trendyol, get matched to another seller's page on Hepsiburada, or hit "invalid GTIN" on Amazon. This guide settles the barcode question for good.
Concepts: GTIN, EAN, UPC, Barcode
- **GTIN:** the umbrella term for a product's global identity number
- **EAN-13:** the 13-digit GTIN type common in Europe/Turkey
- **UPC-A:** the 12-digit North American type
- **Barcode:** the striped representation of these numbers — the number is the identity, the barcode is its notation
What marketplaces call a "barcode" is actually the GTIN number.
What Marketplaces Expect
| Marketplace | Expectation |
|---|---|
| Trendyol | A unique barcode per product + variant; self-generated codes accepted |
| Hepsiburada | GTIN matching into the shared catalog; wrong code = wrong product page |
| Amazon | Official GS1-registered GTIN; a GTIN exemption can be requested |
Critical distinction: Trendyol accepts self-generated numbers; Amazon checks GS1 registration. Plan GS1 membership or a GTIN exemption before launching your own brand on Amazon.
Generating Barcodes for Your Own Products
- List products and variants (each color/size its own row)
- Assign a unique code per row — our [barcode generator](/arac/barkod-olustur) produces EAN-13, Code128 and more, with bulk ZIP and A4 label PDF output
- Record the same code in both the marketplace panel and your stock list
- Stick labels on packages — scanning in the warehouse/returns transforms operations
Printing a QR code on cartons adds a practical layer for internal logistics.
The Cost of Wrong Barcodes
- **Wrong matching:** your product binds to an unrelated page in shared catalogs
- **Variant chaos:** one code across two sizes makes returns unmanageable
- **Catalog lock:** fixing a wrong GTIN later usually requires a support ticket
FAQ: "Can I just type a random number?"
It technically works on Trendyol but carries two risks: colliding with a real product's GTIN, and recoding your whole catalog when you later expand to Hepsiburada/Amazon. Systematic codes take five minutes now; fixing them later takes weeks.