Validates Telephone for Brazil and United States and test it with matchers in a simple way.

Library for validating unchangeable attributes.

Validates if an attribute has a valid xml content or a xsd valid content.

Library for validating urls in Rails.

Adds validation methods considering different country zip code formats. Currently, we can validate 130 countries.

Provides an extensible hook for adding custom html attributes to input elements based on validation rules defined in your model.

Delegates validation between objects

validation_examples_matcher provides rspec matcher testing validations with examples.

Shows what a field expects before validation fails — complementary to ActiveModel errors.

Use reflection to spec ActiveModel validations

Scope ActiveModel validations

A extension activemodel's validations to validation step by step.

A collection of delicious Rails validators

Validaty has basic validations for Rails application

contextual validations for controllers and wanna learn to do other stuff good too

ActiveModel validation for credit card number.

Your favourite validations with Ruby

Valid-env allows you to specify the environment variables that are required, those that are optional, and those that depend on one another, and will throw a useful error message immediately if something is missing.

Extension to ActiveModel for validating hostnames

VAT Identification Number data object and validator