lxberlin/netefx-validator (packagist): NetefxValidator is a class for form validation, so it replaces the RequiredFields() validator. Features: A lot of build in validationrules - logical rule combination - validationrule for unique database fields - custom validation functions - works in getCMSValidator() in Modeladmin - There is no javascript validation at all. So you can disable js-validation in your _config.php
Keywords: validator|validation|silverstripe