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GMC Product Identifier Error Checker

Upload a Merchant Center affected-products CSV, a Shopify or WooCommerce product CSV, or paste a feed URL note. The checker groups GTIN, MPN, brand, barcode, and identifier_exists problems into a product-level fix list.

4 rows checked3 affected rows
High
Invalid GTIN format or check digit

Rows with a non-numeric GTIN, unsupported GTIN length, or failed check digit.

1 row(s). Fix source: Fix the source barcode/GTIN field in Shopify variant barcode, product vendor/brand, the Google & YouTube app, or your feed app mapping.
Medium
SKU may be used as MPN

Rows where MPN equals SKU or looks like an internal store code.

2 row(s). Fix source: Use the manufacturer part number when one exists. Do not automatically map Shopify SKU to MPN.
What this can detect

Invalid check digits, missing GTIN, missing MPN + brand, duplicate barcodes, and identifier_exists mismatch.

What this cannot prove

It does not verify GS1 ownership, inspect your Merchant Center account, or guarantee listing approval.

Where to fix

Use the output to decide whether the source is Shopify, WooCommerce, GMC feed rules, or a feed app mapping.

Fix invalid GTINMissing identifier guide

Use this before rewriting feed rules.

Product identifier errors often start in the source catalog: Shopify barcode, WooCommerce GTIN fields, brand mapping, or a feed app override. The checker groups the problem before you touch Merchant Center rules.

Keep the boundary clean.

This validates field shape and likely repair source. It does not confirm GS1 ownership, policy compliance, account status, or final Google approval.

Related resources

Move from product-level diagnosis into the fix page that matches the error shown in Merchant Center.

Fix pageInvalid GTIN in Google Merchant Center

Check length, check digit, internal SKU misuse, and Shopify barcode source issues.

Open resourceFix pageMissing identifiers: GTIN, MPN, and brand

Decide whether to add GTIN, MPN + brand, or review identifier_exists=false.

Open resourceFree toolFree GMC Misrepresentation Precheck

Check public merchant trust signals after product identifier errors are grouped.

Open resourcePaid auditGMC Misrepresentation Audit

Order a broader merchant trust audit for policy, product, schema, contact, and proof gaps.

Open resourceShopifyShopify SEO Audit

Audit Shopify theme output, product schema, collections, variants, apps, and merchant trust.

Open resource
FAQ

Questions before uploading product identifier data.

Is this a Google Merchant Center verdict?

No. It is a field-level diagnostic for product identifiers. It does not inspect your Merchant Center account or guarantee approval.

Can this verify whether a GTIN is officially assigned by GS1?

No. The checker validates GTIN length and check digit only. It does not verify official GS1 ownership or brand assignment.

What is the difference between GTIN, UPC, EAN, MPN, SKU, and brand?

GTIN is the global trade item number family, including UPC and EAN. MPN is the manufacturer part number. SKU is usually an internal store code. Brand identifies the maker or brand owner.

Should I set identifier_exists to false?

Only when the product truly has no manufacturer-assigned GTIN, MPN, or brand identifier. Do not use false just to suppress Merchant Center errors.

Why does Shopify barcode not appear as GTIN in Merchant Center?

The issue is usually in variant barcode data, the Google & YouTube app, a feed app mapping, or a Merchant Center feed rule that overrides the source value.

Can I upload Merchant Center affected-products CSV?

Yes. The checker is designed for affected-products CSV exports and product catalog CSVs. The data is processed in the browser.

Does this replace my feed app?

No. It helps identify where the field problem likely starts. The actual repair still happens in Shopify, WooCommerce, a feed app, or Merchant Center rules.

Can agencies use this for client stores?

Yes. Agencies can use it as a first-pass triage before producing a client fix list or ordering a deeper feed identifier audit.