If you want to decouple validations from model it would be probably the easiest solution

Add social network friendship features to your Active Record models.

simple rails html validator

Rails imei validator based on Luhn algorithm.

a class to validate ip. it builded for rails

Provides a DSL for common validation formats like Date, Array, DateTime etc.

expose presence-validation in a more controller-friendly manner

rails_react_errors standardizes validation and API error responses in a React-friendly JSON format.

Ruby on Rails is a full-stack web framework optimized for programmer happiness and sustainable productivity. It encourages beautiful code by favoring convention over configuration.

Ruby on Rails is a full-stack web framework optimized for programmer happiness and sustainable productivity. It encourages beautiful code by favoring convention over configuration.

a class to validate uris. it builded for rails

Rails UseCase and Service classes

Validates whether associations are uniqueness when using accepts_nested_attributes_for.

Rails Validation API provides a powerful for validating request parameters in Rails applications. Features include automatic validator loading based on controller/action names, nested parameter validation, custom error handling, and seamless integration with Rails controllers through concerns. Perfect for API applications requiring robust parameter validation with minimal boilerplate code.

HMAC Validation for Rails.

Client Gem for Rainmaker LRO

Parser for range sentences like '1990; 1995-2000; 2005'

ActiveModel validator for ranges

Model-wrappers to customize ransack search

Services for Ruby on Rails.