A recent scan of almost 8,000 mostly Shopify stores by ProductSeen flagged 77% of them for products without barcodes or part numbers. Even on its stricter measure, 58.7% showed no GTIN or part number on any product page it checked. It's a vendor study, so I treat the exact numbers with care, but they match what I see in audits.

What a GTIN is, in plain words

It's the number under the barcode on your pack. In India that's usually a 13-digit EAN, and codes issued by GS1 India start with 890.

Why search engines care

Google says products without unique identifiers are hard to classify, and that it can't be sure of accurate matching when the GTIN is missing. Google also reports that retailers who added correct GTINs saw about 20% more clicks on average. For AI shopping answers the logic is the same: the barcode is how a system knows the serum on your site is the same serum it saw on a marketplace and in reviews.

My pre-launch GTIN checklist

1. Look for barcodes you already have. If you sell on Amazon, Flipkart or a quick-commerce app, you probably have GS1 barcodes already. Use the same numbers.
2. One GTIN per variant, not per product. A 50 ml and a 100 ml bottle need different barcodes. So do two shades.
3. Fill the Barcode field in Shopify for every variant. This is what your feed app and theme read.
4. Check the markup. View the page source (Ctrl+U) and search for "gtin". If it isn't in the Product JSON-LD, your theme isn't printing it even though the admin field is filled.
5. Check the feed. In Merchant Center, look for identifier warnings after the next sync.
6. Applying to GS1 India? Count future variants first. Only the brand owner can apply, it usually takes 7 to 10 working days, and the barcode quantity can't be changed later.

Two things I never do

• Buy cheap barcodes from resellers. They often aren't registered to your brand, so they can match the wrong company's product.
• Make one up. Google's own advice is "when in doubt, don't provide a GTIN". OpenAI's product feed spec says the same: don't invent a value to fill a gap.

Where this fits

GTINs are one part of a bigger problem: your page, your schema and your feed need to tell the same story about price, stock, reviews and identifiers. I covered the full set of checks, with Shopify fixes and an INR JSON-LD example, in my product page SEO checklist for Google and AI shopping.

If you run a D2C store, check five product pages tonight. If the gtin line is missing from the source, you've found your first fix.

I'm Ankit Prajapati, and I work on SEO and generative engine optimisation. Here is how I explain the difference to teams who only track rankings.

Rankings measure position. AI visibility measures presence.

A rank tracker records where a page sits in a list of results for a keyword. An AI answer has no list. ChatGPT, Gemini, Perplexity and Google AI Overviews write a fresh answer for each prompt, and that answer either mentions your brand or it doesn't. A page can rank well on Google and still be missing from AI answers completely.

That's why the metrics are different:

Attribution is different too. Search Console gives you clean click data. AI influence often shows up indirectly, as branded searches, direct visits and referral visits from assistants in GA4.

Why this matters now

Two data points explain why this matters. Ahrefs studied 300,000 keywords in December 2025 and found that an AI Overview correlated with a 58% lower average click-through rate for the top-ranking page. That's a correlation, not proof of cause, but it's a big one. On the other side, Opollo looked at 312 IT and technology service firms and found that AI referral visitors converted at an average of 14.2%, against 2.8% for Google organic.

So you get fewer clicks from classic results and better visitors from AI answers. If your dashboard only shows the first trend, you're making decisions with half the data.

How to add AI visibility to your reporting

You don't need to throw anything away. Add a layer:

1. Write 15 to 25 conversational prompts in three groups: direct comparison, category recommendation and problem-based questions.
2. Track ChatGPT, Gemini, Perplexity and Google AI Overviews or AI Mode to start.
3. Connect GA4 so AI referral visits sit next to mentions.
4. Review monthly. List prompts where you're missing, wrong claims about your brand and newly cited sources, then update the matching pages, FAQs and comparison content.

Expect baseline data within days, but expect real movement over months, not weeks.

Picking a tool

You can run this manually in a spreadsheet at first. When it grows beyond that, tools range from budget options like OtterlyAI and LLMrefs to suite add-ons from Semrush, SE Ranking and Ahrefs, up to enterprise platforms like Profound. I wrote this comparison of 11 tools for tracking brand mentions in ChatGPT, Gemini and AI Overviews, including how to test each one's accuracy before you pay.

Rankings tell you how Google sees you. AI visibility tells you whether the assistant your buyer trusts recommends you. Track both.