Automatically pass attributes through Sanitize before validation

Param checker adds a before filter for each api to do the validation

Rails Validations for typically UK specific data

Hash validation for 'options'-like methods.

Validations is a library for validating data structures.

html_pretty is yet another HTML prettifier. It purposefully does not do parsing or validation.

Three level validation on email addresses for ActiveRecord.

Sets blank attributes to nil as part of validation

Validations for european countries VAT numbers

ActiveModel validation for credit card number.

Allow for validation of only some attributes

A collection of various validators for Rails forms

Adds activemerchant gateway support for hash validation, querying transactions, and submitting payment via hosted forms

Library to parse X12 messages and manipulate their loops, segments, fields, composites, and validation tables.

ActiveRecord model validation against stopforumspam.com (Rails 3)

BagIt package generation and validation

Epic validator, wraps validation for HTML, JavaScript and CSS.

Apply ActiveModel validations at a model instance level

NIS validation for ActiveModel

Some extra sensible validations