GTIN Catalog Check Digit Workbench

How to use GTIN Catalog Check Digit Workbench

Check a catalog list before passing it to another system. Each complete source identifier receives an explicit format and arithmetic result, while leading zeros, duplicates and invalid rows remain visible. A matching check digit helps review transcription; it does not identify a product or establish GS1 allocation, ownership or registration.

1. Paste complete source identifiers or choose one local UTF-8 text file; a selected file takes priority.
2. Choose JSON for exact source evidence or CSV for a row review, then run the local check.
3. Inspect mismatches and unsupported rows. Import CSV identifier columns as Text, and verify allocation or product identity separately.

Good to know

• At most 50,000 UTF-16 characters, 100,000 UTF-8 bytes, 1,000 physical rows and 128 UTF-16 characters per line. A nonempty file is limited to 100,000 bytes and a 5-second read. Complete JSON is capped at 1,000,000 characters/bytes and CSV at 750,000; both are checked before either result is returned.
• Only complete ASCII-digit strings of length 8, 12, 13 or 14 receive the selected weighted modulo 10 check. No trimming, Unicode digit conversion, label/hyphen removal, missing-digit inference, source correction, identifier conversion or deduplication occurs. An all-zero string may match arithmetic without being issued.
• LF and CRLF are retained in exact JSON source. Blank physical rows are reported; a final newline terminates its preceding row without adding a synthetic row. One initial BOM is retained but excluded from the first analyzed identifier. Other BOMs remain invalid row text. Bare CR, forbidden controls/direction marks/noncharacters, unpaired surrogates and malformed UTF-8 cause whole-operation refusal.
• Offsets are zero-based UTF-16 and UTF-8 source positions excluding row terminators. CSV quotes all fields. Source cells beginning with a tab, or an optional BOM and ASCII spaces/tabs followed by =,+,-,@, receive an apostrophe prefix; this selected policy does not certify every spreadsheet importer. JSON keeps originals. Explicitly import identifier/source columns as Text to retain leading zeros.
• This is arithmetic and source-shape evidence only. It does not establish GS1 registration, prefix allocation or ownership, an actual item, barcode scanning quality or marketplace acceptance. No GS1 database, external service, product lookup, AI/Digital Link parser, SSCC/GMN review or barcode generator is used.