Open-source alternatives to Validate.js

Vee-validate is a form validation library and state management tool for Vue applications. It enables the validation of user inputs through declarative rules and tracks form metadata, including submission status and dirty states. The library functions as a wrapper for integrating external schema validation libraries to enforce consistent data shapes. It also serves as an internationalized framework for displaying translated error messages and localized feedback. The project covers broad capability areas including form state management, the handling of complex nested data structures, and the s

Zod is a TypeScript-first schema declaration and validation library designed to ensure end-to-end data integrity. It functions as a runtime type guard, allowing developers to define complex data structures through a declarative, chainable syntax. By using these schema definitions, the library automatically derives static TypeScript types, eliminating the need for manual type duplication and ensuring that runtime data matches expected application contracts. The library distinguishes itself through functional schema composition, which enables the creation of hierarchical structures by nesting a

class-validator is a TypeScript class validation library that uses decorators to define constraints and rules for object properties. It functions as a decorator-based schema validator that ensures data integrity and structural correctness through a combination of synchronous checks and promise-based asynchronous rules. The library provides a recursive validation system for checking complex data hierarchies, including nested classes and individual elements within collections. It includes an object property whitelist utility capable of stripping undocumented properties or blocking unknown field

Angular schema form is a framework directive and form component library that automatically generates and validates interactive HTML form controls from standard JSON schemas and companion layout configurations. It translates structured data definitions into customizable user input interfaces, parsing data types and custom rules into native form controls and reusable HTML markup templates. The project provides capabilities for dynamic field management, allowing form elements to show or hide conditionally by evaluating expressions against current model and scope state, and supporting dynamic arr

This project is a jQuery plugin and client-side form validator used to verify web form inputs before they are submitted to a server. It employs a rule-based validation engine to check user input against predefined or custom rules to ensure data integrity in the browser. The tool is designed as an ARIA-compliant validation system, using accessibility attributes to link error messages to input fields. This ensures that screen reader users are notified when a field contains an invalid value during the form submission process. The system supports remote server validation via asynchronous HTTP re

Parsley.js is a JavaScript form validation library that provides a client-side data validator for verifying input correctness before submission. It functions as an HTML attribute-based validator, allowing constraints to be defined declaratively within HTML data attributes to enforce rules without requiring custom scripts. The framework distinguishes itself through a customizable validation system that supports user-defined rules and custom error message templates. It includes a remote validation interface to verify form values against server endpoints via asynchronous network requests and sup

This project is a schema-based form generator for Vue.js that constructs interactive user interfaces by parsing structured data configurations. It automates the creation of form layouts, data binding, and field rendering, eliminating the need for manual template creation for individual forms. The system distinguishes itself through a registry-based architecture that allows for the integration of custom input components. By mapping specialized field types to the generation engine, developers can extend the library to handle unique data types or complex interface requirements that fall outside

v8n is a JavaScript data validation library used to verify that values, objects, and arrays meet specific criteria. It functions as a schema-based validator and an asynchronous validation engine, utilizing a fluent API to construct sequences of chainable rules and constraints. The framework is distinguished by its ability to execute promises and network requests during the validation process to determine if a value is valid. It allows for the creation of reusable validation schemas and provides a customizable rule framework where users can define their own logic and configure how error result

This project is a Python implementation of the JSON Schema specification, providing a library for verifying that data instances conform to defined schemas. It serves as a data validation framework capable of validating both the data itself and the schemas against official meta-schemas to ensure structural correctness. The library features a schema reference resolver that maps URIs to definitions, enabling the resolution of internal and remote references for modular schema management. It is designed for extensibility, allowing for the definition of custom keywords, custom type-checking logic,

Vibora is an asynchronous Python web framework and built-in HTTP server designed for building high-performance web applications. It utilizes an asynchronous event loop and coroutines to process network requests and serve responses without requiring external server wrappers. The project features a high-performance asynchronous schema validator for request integrity, a non-blocking template engine with support for hot-reloading, and a WebSocket communication server for bidirectional real-time data exchange. The framework covers a broad range of capabilities, including modular route management

imaskjs is a JavaScript input mask library and DOM input manager used to enforce specific patterns, data types, and ranges on user input in real-time. It serves as a data formatting library and input validation tool that transforms raw input values into formatted strings using masks and custom pipes. The project provides dynamic masking capabilities, allowing input patterns to change or switch in real-time based on the characters a user types. It supports complex input constraints including regular expressions, numerical ranges, date-based verification, and character enumerations. The librar

CodeIgniter is a PHP web framework built on the Model-View-Controller pattern, designed for building full-stack web applications. It provides a lightweight toolkit with minimal configuration, organizing application logic into controllers, models, and views for clean separation of concerns. The framework includes a fluent query builder for constructing SQL statements programmatically, PSR-4 autoloading with namespace mapping, and a service-based dependency injection container for managing shared class instances. The framework distinguishes itself through its comprehensive set of built-in tools

Backbone.validation is a JavaScript library designed to enforce data integrity within Backbone.js models. It provides a framework for defining declarative validation schemas that intercept attribute changes, ensuring that data meets specified business requirements before it is committed to the model. The library distinguishes itself by tightly coupling model-level validation with user interface components. It features an event-driven binding system that monitors model states and automatically triggers interface updates, providing real-time feedback as users interact with forms. This approach

This library is a Ruby-based validation engine designed to verify JSON data structures against official schema specifications. It ensures data integrity by confirming that objects, strings, and files conform to defined structural constraints, while also validating the integrity of the schema definitions themselves against official metaschema standards. The project distinguishes itself through a highly modular architecture that allows for deep customization. Users can register custom validation rules and format handlers to enforce project-specific business logic that extends beyond standard sp

Hibernate Validator is a reference implementation of the Jakarta Validation specification, serving as a framework for enforcing data integrity across Java applications. It functions as a declarative validation engine that processes object constraints to ensure that application state remains consistent. By utilizing metadata-driven rules, the library validates object properties, method parameters, and nested collections to maintain data standards throughout an application's layers. The library distinguishes itself through its ability to perform static analysis on validation configurations, ide

ozzo-validation is a programmable data validation library for Go that verifies structs, maps, and primitive types using a declarative, rule-based approach. It functions as an interface-based validator, allowing for the recursive checking of nested data structures and custom types without the use of struct tags. The framework distinguishes itself as a context-aware validation engine, supporting the propagation of request-scoped data to rules that depend on external state. It provides extensive extensibility through custom rule definitions and the ability to override default failure text with l

This project is a reactive state management library designed for handling complex form data and validation logic. It utilizes observable-based patterns to synchronize user interface components with underlying data models, ensuring that form states remain consistent throughout an application. The library provides a structured approach to managing form initialization, field tracking, and lifecycle events. The library distinguishes itself through its support for deeply nested data structures and hierarchical composition, allowing for recursive validation and dynamic updates within complex object

Yup is a JavaScript schema validation library used to define data shapes and validate runtime values. It functions as an object schema validator and a data coercion engine, allowing developers to transform raw input values into desired types before performing validation checks. The library is distinguished by its support for dynamic schema validation, where rules can be adjusted at runtime based on sibling field values or external context. It also enables recursive data structuring for polymorphic fields and provides a system for extracting static TypeScript interfaces from runtime schema def

Pandera is a data pipeline validation framework and statistical type validation tool. It functions as a library for defining and enforcing schemas on datasets to ensure data quality and consistency, specifically providing validation capabilities for Pandas dataframes. The project includes a schema inference tool that automates setup by analyzing existing dataset samples to generate validation schemas. It also serves as a synthetic data generator, creating artificial datasets based on predefined schemas to verify data-producing functions. The framework covers data engineering quality assuranc

web.py is a minimal Python web framework that provides the core components needed to build web applications: URL routing, template rendering, database access, form handling, and session management. The framework uses a convention-based approach where URL patterns are automatically mapped to handler classes based on their names, eliminating the need for manual route configuration. It exposes applications as WSGI callables, making them deployable with any WSGI-compliant server. The framework distinguishes itself through its metaclass-driven auto-discovery system, which automatically registers h

Joi is a JavaScript data validation library used to define schemas that ensure the structure and data types of objects remain consistent. It functions as a schema-based validator and object schema definition tool, preventing invalid information from entering an application by checking data against predefined constraints and rules. The library employs a chainable fluent interface and a constraint-based validation engine to build complex validation pipelines. It utilizes recursive tree traversal to validate nested data structures and a type-coercion pipeline to transform input values into the t

Backbone Forms is a schema-driven library designed to automate the generation and validation of HTML forms within the BackboneJS ecosystem. It functions as a framework for building data entry interfaces that bind directly to application models, ensuring data integrity through a combination of schema-level rules and model-level constraints. The library distinguishes itself through a modular architecture that supports the creation of custom input editors and the use of pluggable HTML templates. This allows for the management of complex, hierarchical data structures, including nested objects and

This project is a jQuery-based form validation library designed to verify HTML form input values on the client side before submission. It functions as an input validator that enforces data integrity constraints through rule-based verification and value normalization. The library focuses on web accessibility compliance by linking error messages to input fields via ARIA attributes, ensuring that screen readers can announce validation failures to the user. The system supports the creation of custom validation rules and the transformation of raw input strings through a normalization pipeline. Co

Joi is a JavaScript data validation library used to define schemas that validate, cast, and sanitize data objects. It functions as an object schema validator and parser, ensuring that input data matches specific types and formats before it is processed by an application. The library features a conditional validation engine capable of dynamic schema enforcement, where validation logic and dependencies change based on the values of other keys within an object. It also serves as a data casting and sanitization tool, transforming input values into target types and removing sensitive keys from the

Nuxt UI is a comprehensive Vue component library built for the Nuxt ecosystem, providing over 125 production-ready, WAI-ARIA compliant components for building modern web applications. The library offers a complete design system with Tailwind CSS theming, supporting dark mode, custom color palettes, semantic color aliases, and runtime theme switching through CSS design tokens. It includes built-in internationalization for over 50 languages, server-side rendering compatibility, and a Figma kit that mirrors the code components for design-to-development consistency. The library distinguishes itse

PydanticAI is a Python framework designed for building production-grade autonomous agents. It provides a unified interface for interacting with diverse language models, enabling developers to construct agents that perform complex tasks through structured data validation, tool execution, and multi-turn conversation management. The library centers on type-safe schema enforcement, ensuring that model inputs and outputs remain consistent and reliable throughout the agent's lifecycle. The framework distinguishes itself through a robust architecture that emphasizes modularity and testability. It ut

This project is a declarative framework for building interactive web forms by parsing JSON Schema definitions. It functions as a component-based generator that automatically maps schema constraints to input fields and validation logic, ensuring that data collection remains consistent with defined structures. The library distinguishes itself through a registry-based architecture that allows for extensive customization of the user interface. Developers can override default widgets, field templates, and layout structures to accommodate unique data types or specific design requirements. It suppor