Nested validations allow a parent's validity to include those of child attributes. Errors messages will be copied from the child attribute to the parent.

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

Create K-fold splits from data files and assist in training and testing (useful for cross-validation in supervised machine learning)

A Rails engine that provides a response mechanism for Let's Encrypt ACME - Simple HTTP - Identifier Validation Challenges on 12 factor apps like those deployed on Heroku as well as the rake task to generate the certificate from your local machine.

Rails plugin that uses George Carlin's list of seven dirty words (aka swear words, aka cuss words) to check for decency on ActiveRecord model attributes.

Numverify: Global Phone Number Validation & Lookup JSON API

Resulting is a library for graceful result handling. It provides a result class with a few methods that can be used as a mixin. Using these results, they can be passed to save and validation services which handle them gracefully, returning early when there is a failure, or ensuring success for al...

functional classes with param validations for cautious developers

Inspector is a validation library for Ruby with zero assumptions

Plinko helps you create validators that collect all validation errors instead of breaking on the first failure.

Command line tool to automate creation of chef orgs, chef policy repositories, and validation key integration with vco

Validation of popular Polish codes, such as PESEL, NIP, REGON, post codes, car registration numbers, credit card numbers and anything really that can be helpful in advanced commercial application for Polish customers.

GuideRail transforms various data sources into safe, immutable `Data` objects. By leveraging the robust validation capabilities of `dry-schema`, it provides a clear and declarative way to define, validate, and instantiate your data structures.

Json Schema Client is a Ruby client for JsonSchema with validation and hypermedia.

Custom ActiveModel::Validations to Make Your Life Easier

Scrivener removes the validation responsibility from models and acts as a filter for whitelisted attributes. Works with Opal.

Provides wrapper functionality and authentication for REST and RPC HTTP requests to OpenSocial-compliant endpoints, along with validation of incoming signed makeRequest calls.

Ruby on Rails plugin for HTML validation and link checking

A small library for manipulating form-based data with validations and attributes coercion.

Hval 🐳 is hash validation gem