diff --git a/README.md b/README.md
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@@ -1703,6 +1703,7 @@ See [go-hardware](https://github.com/rakyll/go-hardware) for a comprehensive lis
 
 *Libraries for validation.*
 
+* [checkdigit](https://github.com/osamingo/checkdigit) - Provide check digit algorithms (Luhn, Verhoeff, Damm) and calculators (ISBN, EAN, JAN, UPC, etc.).
 * [govalidator](https://github.com/asaskevich/govalidator) - Validators and sanitizers for strings, numerics, slices and structs.
 * [govalidator](https://github.com/thedevsaddam/govalidator) - Validate Golang request data with simple rules. Highly inspired by Laravel's request validation.
 * [jio](https://github.com/faceair/jio) - jio is a json schema validator similar to [joi](https://github.com/hapijs/joi).