Awesome validation and object matching library

It will handle validations inline

HMAC Validation for Rails.

automatically add client-side validations

Use reflection to spec ActiveModel validations

Another validation library

A collection of Regular Expression validations

Add more validation methods for ActiveRecord columns like email, url, and creditcard.

Automate the writing of validations, relations in files and specs. Create boilerplate validation in models, specs, migrations. This specs are generated based on rspec, shoulda-matchers and factorygirl

Reuse your Rails model validations on the client-side.

It will handle ajax validations.

Validation of params for Sinatra

ActiveRecord extension that allows to infer validation rules from database

simple_form with client validations

Extra matchers to test model validation

ActiveRecord::Enum fire SQL request and bypass ActiveModel::Validations, this let you play with enum and validation

Declare ActiveModel validations fluently

RailsAjaxFormhandler is a lightweight Javascript-plugin which submits your form automatically and displays server responded validation-errors by adding styles and error-messages to the invalid input fields.

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.

RSpec matchers for testing ActiveModel custom validations in isolation from your application's models