Validations is a library for validating data structures.

Three level validation on email addresses for ActiveRecord.

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

Object validation inspired by RSpec.

Simple DSL for datatype validation for basic data types.Inspired from GRPC DSL. Since ruby is dynamic language, datatype validator helps to reduce runtime errors by validating structure before processing

YAML files loader with validation

Simple validation library with virtus integration

ActiveRecord model validation against stopforumspam.com (Rails 3)

IAP and IAB receipt validation module.

A rails plugin to set the digested value before validation and validate uniqueness.

ActiveRecord: Simple filtering for html as validation.

Easily add Judge client side validation to your Formtastic forms.

Built for Developers. Ideal for MVPs, product ideation and validation.

Provides an easy way to add model-based validations to excel files.

Language Independent Validation Rules. Implements 2.0 specification

A Guilded (http://github.com/midas/guilded/tree/master) component that will reflect ActiveRecord validations and use them to live validate forms.

This gem wraps the guards.js jQuery validation library as a Rails asset gem.