Check Digit Validator
Validates IBAN/ISBN/EAN/Luhn checksums and finds the one wrong digit
| Endpoint | https://check-digit.gumballtools.com/api/mcp (streamable-http) |
|---|---|
| Registry version | 0.1.0 |
| Now | 1 tools · grade D (54) · pin ts_7d2c378e8f3f9e06496beb95abc23d22 · protocol 2025-06-18 |
| First / last listed | 2026-10-27 08:27 UTC / 2026-10-27 08:27 UTC |
| Grade over time | 2026-10-27: D (54), 1 tools |
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Tools: run
run | Validate the check digit(s) on an IBAN, ISBN-10, ISBN-13, EAN-13, UPC-A, or Luhn-checked card number, and when it fails, try to say which digit is wrong.
Use this instead of computing the checksum yourself. Mod-97 arithmetic on a rearranged 15-34 character IBAN, or a weighted sum mod 10/11 over 10-19 digits, is exactly the kind of long deterministic calculation language models get wrong silently params: input*, format* |
Entries describe changes in tool definitions. They are not statements about a server, its quality or its author. The grade measures how the tool definitions fit model providers (token cost, schema compatibility, confusable names) as scored by the ToolFit engine at the time of the listing. JSON: append .json. Opt-out: how or hello@youraitools.co.