GTIN validation
GS1 GTIN-8/12/13/14 (EAN-8, UPC-A, EAN-13, GTIN-14) — checksum: GS1 mod-10 (weights 3,1). Free in your browser, or over the JSON API.
What it is
GS1 GTIN-8/12/13/14 (EAN-8, UPC-A, EAN-13, GTIN-14). CodeCheck verifies three things separately — format, length and check digit — and returns the expected and provided check digit, so a failed value tells you exactly what is wrong instead of just saying no.
Algorithm
GS1 mod-10 (weights 3,1). The answer is derived from the value itself, with no database lookup and no third-party call, so it is deterministic, fast and privacy-safe.
Examples
| Value | Result | Expected | Provided |
|---|---|---|---|
| 4006381333931 | valid | 1 | 1 |
| 036000291452 | valid | 2 | 2 |
API
curl "https://<your-worker>.workers.dev/v1/validate/gtin/4006381333931"
This type has a single trailing check digit, so CodeCheck can also compute it:
GET /v1/complete/gtin/{body}
Try it in the browser demo — the demo runs the same code offline.