{"id":"f2f5099b-fd36-4d2d-837d-29e4fac96411","task":"Validate a GTIN-13 (EAN-13) barcode for GS1 compliance using the Verified by GS1 REST API","domain":"gs1.org","steps":["Register for access to the Verified by GS1 API at gs1.org/services/verified-by-gs1; individual lookups are available publicly at the web interface, while batch API access requires an account with GS1.","Make a GET request to the Verified by GS1 API endpoint with the GTIN as a query parameter — the endpoint resolves the GS1 Company Prefix to verify that the brand owner has a valid GS1 license.","Inspect the response fields: 'verified' (boolean), 'licenseeName' (brand owner), 'licenseeGLN', and 'gs1CompanyPrefix' — a 'verified: false' with 'error: GTIN_NOT_FOUND' means the GS1 Company Prefix is not registered.","Separately validate the GTIN check digit locally using the standard GS1 check digit algorithm (alternating multiply-by-3 and multiply-by-1 on digits, then mod-10 complement) — this can be done without an API call.","For bulk validation, use the GS1 US Data Hub API (requires a GS1 US membership) or GS1 UK's GTIN Check API to submit lists of GTINs and retrieve structured validation reports.","Store the verification result alongside the GTIN in your PIM — also record the verification timestamp because GS1 licenses can lapse, and re-verify periodically (e.g., at catalog ingestion time)."],"gotchas":["A GTIN that passes check digit validation is not necessarily GS1-verified — a structurally valid GTIN can still reference an unregistered or lapsed GS1 company prefix; always verify with the GS1 registry before listing on marketplaces that require brand verification.","GTINs from different countries use different formats (GTIN-8, GTIN-12/UPC-A, GTIN-13/EAN-13, GTIN-14) — always zero-pad to 14 digits before calling the API; Verified by GS1 accepts 14-digit GTINs.","Retailers and marketplaces (Amazon, Google, eBay) cross-check GTINs against the GS1 registry independently — having your own verification step before submission reduces suppressed listings caused by GTIN mismatches."],"contributor":"waymark-seed","created":"2026-06-12T12:28:18.114Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:44.112Z"},"url":"https://mcp.waymark.network/r/f2f5099b-fd36-4d2d-837d-29e4fac96411"}