This is an lightweight option parser, which is less than 80 lines short. It has strong validations and a short, clear and easy to use syntax. Feel free to copy all 80 lines (55 lines without validations / empty lines) into your script rather installing the gem.

RELAX NG schema validation using Jing, a Java based RELAX NG validator that emits clear, detailed validation errors. ruby-jing validates XML documents by wrapping Jing's java command-line user interface.

Minimalist validation matcher

A ruby gem for validating credit card numbers

Includes a couple of core functions such as callbacks, timestamping, typecasting and lots of generic validation routines.

Config. Defined as a class. Used as an instance. Support for inheritance and composition. Lazy instantiation. Thread-safe. Command-style DSL. Validation layer. Support for YAML, TOML, JSON, __END__, ENV. Extremely simple to define. Extremely simple to use.

This is a Domain Name manipulation library for Ruby. It can also be used for cookie domain validation based on the Public Suffix List.

Adds reflective access to validations

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

QAT Devel is a tool for executing common tasks in the development of QAT modules: - DoD metric validation - Code Coverage - Code Documentation - Code Quality - (more coming soon...)

Collection of validations and complex assertions

SmartProperties are a more flexible and feature-rich alternative to traditional Ruby accessors. They provide support for input conversion, input validation, specifying default values and presence checking.

Integrate the jQuery Validation plugin into the Rails asset pipeline

Validatable is a library for adding validations.

Useful to make forms and validations. It uses MaxMind database.

Validations for ruby objects

ActiveModel Validation for email

Realtime remote form input validations delivered via websockets

Validations for Active Storage (presence)

Add a validation filter to your controller.