Korean Business Number Validator
Validate Korean business registration numbers (사업자등록번호) with the official checksum. Check multiple numbers at once, one per line. Everything runs in your browser.
FAQ
How are numbers validated?
The 10-digit number is checked with the National Tax Service checksum using weights 1,3,7,1,3,7,1,3,5.
Does a valid result mean the business exists?
No. It only means the format is correct. Actual registration status must be checked on the Korean tax authority's Hometax service.
Are the numbers sent to a server?
No. All validation happens locally in your browser; nothing is transmitted or stored.
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