GTIN Digit Checkerv1.0.0

Enter barcodes or identification codes into the text area to verify their check digits. The tool supports GTIN-8 (EAN-8), GTIN-12 (UPC-A), GTIN-13 (EAN-13), GTIN-14, ISBN-10, and ISBN-13 formats. Each code is validated against its format-specific check digit algorithm, and the result indicates whether the code is valid or invalid.

• Type or paste one or more codes into the Enter one or more codes, one per line text area. Place each code on its own line for batch processing.
• Select a specific format from the Code format dropdown to restrict validation to that type, or leave it set to Auto-Detect to let the tool determine the format based on the code length.
• Press the Validate button or wait for automatic validation after typing. The results table displays each code alongside its detected format, validity status, and expected check digit.
• Hyphens and spaces within codes are stripped automatically before validation. For example, an ISBN entered as 978-0-13-468599-1 or 978 0 13 468599 1 is processed correctly.
• GTIN formats (8, 12, 13, and 14 digits) use an alternating weight algorithm with factors of 1 and 3 applied to the digits, summed, and taken modulo 10. The check digit is the value needed to bring the total to the next multiple of 10.
• ISBN-10 uses a weighted sum with multipliers descending from 10 to 2, taken modulo 11. A remainder of 10 produces the check digit X.
• ISBN-13 follows the same algorithm as GTIN-13 because ISBN-13 codes are a subset of the EAN-13 standard.
• Import a CSV file containing codes in the first column by clicking the Import CSV file input. The tool reads each row and populates the text area for validation.
• After validation, press the Export CSV button to download a CSV file containing the code, detected format, status, and expected check digit for each entry.
• Press Reset to clear all inputs, results, and saved state.

Barcode and ISBN validation applies across retail, publishing, logistics, and data management workflows where accurate product identification codes prevent costly errors.

• Retail inventory management: Verify that product barcodes scanned into a point-of-sale or inventory system carry correct check digits before committing them to the database, reducing misidentified items and checkout errors.
• E-commerce product listing: Validate GTIN-12 and GTIN-13 codes before submitting product feeds to marketplaces such as Amazon, Google Shopping, or Walmart, which reject listings with invalid barcodes.
• Publishing and library cataloging: Confirm ISBN-10 and ISBN-13 codes on book metadata records, ensuring that catalog entries, MARC records, and online bookstore listings reference the correct edition.
• Supply chain and logistics: Check GTIN-14 codes on shipping containers and case packs to verify that outer packaging identifiers are consistent with inner product GTINs, preventing warehouse mispicks and shipment mismatches.
• Data migration and cleanup: Import a CSV of thousands of product codes from a legacy system, batch-validate them, and export the results to identify which entries need correction before loading into a new platform.
• Barcode label printing: Before printing physical barcode labels, validate the numeric code to catch transposition errors or truncated digits that would render the printed barcode unscannable.
• GS1 compliance auditing: Audit an entire product catalog against GS1 standards by batch-checking every GTIN for valid structure and correct check digit, producing a report of non-compliant entries for correction.