Decode iTunes OS X and iOS receipts without remote server-side validation by using the Apple Inc Root Certificate.

Opt-in validations for your ActiveRecord models based on your MySQL database constraints, including text field size, UTF-8 encoding issues, and NOT NULL constraints.

Ruby gem for runtime data validation and monitoring using the contracts approach.

Validate iTunes Transaction and Unified style receipts with local decoding and remote validation.

ActiveModel validations for domains (including TLDs), ip addresses and email addresses with fully localization support.

If you have a presence validation, you'll probably want a non-null constraint to go with it.

Interpol is a toolkit for working with API endpoint definition files, giving you a stub app, a schema validation middleware, and browsable documentation.

Allows defining structure of data and perform validation against it using json-schema

Custom Ruby on Rails form builder that generates GOV.UK elements styled markup for form inputs, including error validation messages.

Data structures, validation, coercion and processing toolkit for Ruby

Adds validation methods to ActiveModel for validating phone numbers.

Interface to the W3C Feed Validation online service http://validator.w3.org/feed/

It provides validation of URIs (URLs) to ActiveModel records and ActionControllers in Rails 3.

Allows testing vor valid html (including html5) and css. In addition you can configure the gem to use a locally installed validation service instead of the online w3c servers

JSON schema validation for Rails

The Google Sign-In API gives OAuth2 JSON Web Tokens (JWT) as response data upon user sign-in. A necessary step for a service provider to trust such a token is validatation. Accepting the token without validation would allow a malicious client to simply assert itself in your system. ...

Provides a form field validation JavaScript library for your Rails application. Built for use with jQuery and Twitter Bootstrap 3. Source code: https://github.com/nghuuphuoc/bootstrapvalidator

Generate jCheck code according to ActiveModel validations

Explicit parameters validation and casting for Rails APIs

Input Mask validation for ActiveModel