ASP.NET MVC Core 2.0 sample project with one input form and Bootstrap 4 beta CSS validation classes. In particular instead of standard ASP.NET MVC validation css-classes "input-validation-error", "input-validation-valid", "field-validation-error" and "field-validation-valid", Bootstrap 4 beta css-validation classes "is-valid", "is-invalid", "invalid-feedback" are set on server and client sides.