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Check Digit Validator

Validates IBAN/ISBN/EAN/Luhn checksums and finds the one wrong digit

likely compatible

Answered an MCP initialize with no credentials; use auth 'None'.

Rule R2a · what this means · Not tested in Copilot Studio.

Registry namecom.gumballtools/check-digit
Endpoint used for verdicthttps://check-digit.gumballtools.com/api/mcp
Transportsstreamable-http
Auth (Copilot Studio setting)None (open)
Last endpoint check2026-10-20T18:11:27Z · initialize OK
GitHubbwalvoord/gumball
Websitehttps://check-digit.gumballtools.com
Version0.1.0
Registry updated2026-09-05
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Is this wrong or out of date? Email us. Data built 2026-10-20.