Now you can validate VAT using the European service called VIES, to ensure it exists. Only require this gem and call validate_as_vat_number on your VAT field, in an Active Record object.

Validates wether an association belongs to the same owner

Validates CNPJ and test it with matchers in a simple way.

Brazilian zipcode validations for ActiveRecord, integrated with correios-cep gem.

The purpose of this gem is to validate countrycodes in ISO 3166-1 alpha-2 format

Validates CPF and test it with matchers in a simple way.

Validates CURP and test it with matchers in a simple way.

ActiveRecord callback which handle the name duplication in your model.

Some description for validates-gem

Rails 2 and Rails 3 plugin. Validates e-mail address format (RFC2822 and RFC3696) and whitelist/blacklist the domain part.

Validates Host, Domain and IP and test it with matchers in a simple way.

Validate iban

Validations for making ActiveRecord objects immutable.

Validates IPv4 and IPv6 addresses

Rails plugin that provides a validates_ip_format_of method to ActiveRecord models. IPs are validated by regexp. IP validation. Validate IP.

Validates uniqueness of has_many children

ActiveModel validator that ensures Word-tags hasn't been accidentally pasted into WYSIWYG attributes.

Validate phone numbers against E.164 format with this Ruby on Rails gem

Add to Rails the possibility to validate the quantity of an associate model

Validates mexican RFC and test it with matchers in a simple way.