#check-digit

Add and verify check digits with the standard algorithms — Luhn (mod 10), Verhoeff, Damm and ISO 7064 mod 97-10 — on any number. The generate endpoint returns the check digit(s) and the complete number; the validate endpoint tells you whether a number's check digit is correct. Luhn is the familiar mod-10 scheme behind credit cards, IMEI and many ID numbers; Verhoeff and Damm are single-digit schemes that also catch all adjacent-transposition errors; mod 97-10 produces two check digits and is the scheme used by IBAN. Perfect for generating and validating reference, account, membership and order numbers, and for data-entry integrity. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 4 endpoints. Distinct from credit-card and barcode validators, which apply a fixed algorithm to one specific number format.

api.oanor.com/checkdigit-api

Validate and work with product and publication codes. Check the check digit of any EAN-8, UPC-A, EAN-13, GTIN-14, ISBN-10, ISBN-13 or ISSN code — the type is detected automatically and you get back whether it is valid plus the expected check digit. Compute the missing check digit for a partial code, and validate or convert ISBNs between the 10- and 13-digit forms. Hyphens and spaces are ignored, so you can paste codes straight from a label or catalogue. Pure local computation — no key, no third-party service, instant. Live. 4 endpoints. Built for retail and inventory systems, e-commerce catalogues, publishing, library tooling and data validation. Distinct from barcode image generation, payment-card (Luhn) and IBAN checks.

api.oanor.com/barcodecheck-api