Performs k-fold cross-validation on machine learning classifiers.

Some useful validators for sexy validation.

Delegates validation between objects

A notifier for form validation errors.

Add dimension validation to ActiveModel

Find and report ActiveRecord validation errors.

A gem/plugin for Rails 3+ that enables client-side validation using ActiveModel + HTML5

Simple model and validation mixins for RubyMotion

Robust options validation for methods.

Rails plugin that maps model validations to class names on form elements to integrate with Validatious.

Phone number parsing, validation and formatting

A Ruby wrapper for the World Wide Web Consortium’s online validation services.

Regressor generates regression specs based on ActiveRecord models. Currently relations, validations, attributes, and database indexes are supported.

ActiveRecord Tableless Models provides a simple mixin for creating models that are not bound to the database. This approach is useful for taking advantage of the features of ActiveRecord such as validation, relationships, etc.

Includes a couple of core functions such as callbacks, timestamping, typecasting and lots of generic validation routines.

Machinery is a systems management toolkit for Linux. It supports configuration discovery, system validation, and service migration. It's based on the idea of a universal system description.

Introspects your database string field maximum lengths and automatically defines length validations.

Minimalist validation matcher

cucumber-api allows API JSON response validation and verification in BDD style.

Add a validation filter to your controller.