The distinction
The symbol and the number are separate things
A barcode is a way of writing a number so a machine can read it. Any tool, including this one, can draw a valid symbol around any number you like. What a tool cannot do is give you the right to a number in the global product database.
GTINs are issued by GS1, a not-for-profit standards body with a national organisation in most countries. You license a company prefix and assign item references within it. Retailers, marketplaces and data pools check the registry to confirm that the prefix in a number belongs to the business claiming the product.
You need a licence
When a GS1 number is genuinely required
- Selling through retailers. Any shop that scans your product at a till will ask for a GTIN and will verify it.
- Amazon and most large marketplaces. They check the prefix against the registry at listing time.
- Shopping feeds. Google and Meta match products by GTIN; a bad one suppresses the listing.
- Distributors and wholesalers. Their systems are built around GTINs, and they will not carry a product without one.
You do not
When an invented number is perfectly fine
If the only scanners that will ever see the code belong to you, nothing is being verified and nothing can collide. That covers a great deal of real work:
- Stock control in your own workshop, studio or storeroom.
- Market stalls and craft fairs using your own till app.
- Asset tags on tools, equipment and IT hardware.
- Library, archive and collection catalogues.
- Direct-to-customer sales through your own website, including Etsy handmade listings.
- Internal logistics — bins, shelves, totes, work orders.
For these, Code 128 is usually the better choice anyway, because it carries meaningful text rather than an opaque number. If you do want an in-store retail symbol, the 20–29 EAN prefix range is reserved for internal use and will never clash with a manufacturer's real GTIN.
The grey market
What cheap resold barcode numbers really are
Sites selling GTINs for a few pounds each are generally reselling capacity from prefixes issued to companies before 2002, when GS1 changed its terms to make licences non-transferable and annually renewed. The numbers are structurally valid and will scan. The registry, though, still shows the original licensee as the owner.
In practice that means they may work for a while in less strict channels and fail where it matters: Amazon's GTIN validation, Google Shopping feeds, and retailer onboarding. Because verification has tightened steadily, buying resold numbers is a bet against the direction of travel. If your plan involves retail or a large marketplace, license properly; if it does not, you did not need a GTIN at all.
Practicalities
What licensing involves
You apply to the GS1 organisation in your own country, choose a capacity tier based on how many distinct products you sell, and pay a joining fee plus an annual renewal. Several countries now offer single-number products aimed at businesses with one or two items, which are far cheaper than a full prefix. Prices and tiers vary by country, so check your national GS1 site rather than trusting a figure quoted on a reseller's page.
Once you have the prefix, you assign item references yourself, calculate each check digit — the calculator here shows the arithmetic — and generate the symbols. That last part stays free.
Questions
Frequently asked questions
Can I make up a barcode number?
For codes only your own systems will scan, yes. For anything sold through a retailer or a large marketplace, no — the prefix is checked against the GS1 registry.
Are cheap barcode numbers from resellers legal?
Selling them is not a crime, but the numbers are not licensed to you under current GS1 terms, and major marketplaces increasingly reject them.
What is the 20–29 prefix range?
A block reserved for in-store and internal use. Numbers there are never issued to manufacturers, so they are safe for your own shelf labels.
Do I need a separate number for each variant?
Yes. Every size, colour or pack quantity a customer can buy separately needs its own GTIN.
Does GS1 membership renew annually?
In most countries, yes — a joining fee and then an annual licence fee based on how many numbers you hold.