Rails plugin that uses George Carlin's list of seven dirty words (aka swear words, aka cuss words) to check for decency on ActiveRecord model attributes.

ActiveRecord callback which handle the name duplication in your model.

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

Adds ActiveModel validators for common instant messaging services like Skype and AIM.

Validations for making ActiveRecord objects immutable.

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

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

Validate specific value for Rails

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

validates_schema was developed by: markbates

Makes boolean validations a little cleaner.

Library for validating unchangeable attributes.

Validate uniqueness of multiple newly associated records

Rails plugin that provides a validates_uri_format_of method to ActiveRecord models. URLs are validated by several options.

Provides validates_xml method allowing to validate xml correctness of ActiveRecord attributes.

Library for validating urls in Rails.

Adds basic reflection support to ActiveRecord validations

ActiveModel Interface for validation_reflection

If you need a way to easily skip validations on some attributes and only in certain cases, this gem will allow you to do it in a clean and elegant way.

validations-skipper is a gem that enables objects to skip specified validations with ease. It can be applied to ActiveRecord::Base classes.