Verify a GS1 key's check digit and identify its prefix
Check the GS1 mod-10 check digit on any numeric GS1 key (GTIN-8/12/13/14, GLN, SSCC) and — for GTIN-shaped keys — report which GS1 Member Organisation or numbering scheme the prefix belongs to.
expected_check_digit is returned even when the supplied digit is wrong, because the useful answer to a failed check is which digit it should have been.
Keyless — no API key, no signup. IP-throttled at 300 requests/minute and cached at the edge for 24h, so repeat calls for the same input do not reach origin. Over-rate callers get a 429 with a Retry-After header and a retry_after field — it never silently degrades or returns a wrong answer under load.
Query Parameters
The GS1 key to analyse, e.g. 09506000164908. Hyphens and spaces are ignored.
1 - 64Response
OK
Check-digit and issuing-organisation analysis of a numeric GS1 key.
The input, echoed back unchanged.
True when the key's trailing GS1 mod-10 check digit is correct.
Digit count after stripping hyphens and spaces.
x >= 014
Whether the length is one of the GTIN-8/12/13/14 lengths.
Why the key is invalid, or null when it checks out.
GTIN-length keys zero-padded to GTIN-14; other keys stripped of separators. null when the key could not be read.
The trailing digit supplied by the caller.
"8"
The digit the GS1 mod-10 algorithm requires. Populated even when it disagrees with check_digit.
The three-digit GS1 prefix (digits 2-4 of the GTIN-14). null for non-GTIN-length keys.
Which GS1 Member Organisation or scheme that prefix belongs to. null when unassigned or not GTIN-shaped.