Fynix - Fluent, Modern PHP Validation Library with Nested DTO Support

Fynix is a framework-agnostic PHP validation engine for rules that stay readable as your application grows. Build a rule with the Rule facade, compose it with fluent constraints, and return the same structured errors from a field, DTO, or nested object graph.

Validation that reads like policy

use Fynix\Rule;

$email = Rule::email('email')
  ->required()
  ->max(180);

$error = $email->validate('not-an-email');

Rules are immutable, chainable, and built through the public facade. Use the same fluent language for a one-off value or a complete DTO.

One API, every boundary

use Fynix\RuleSet;
use Fynix\ValidationHandler;
use Fynix\ValidationRegistry;

final class User
{
    public string $firstName = '';
    public string $email = '';
}

ValidationRegistry::register(
    User::class,
    static fn (RuleSet $rules): array => [
        $rules->string('firstName')->min(2)->max(50),
        $rules->email('email')->max(180),
    ]
);

$user = new User();
$user->firstName = 'A';
$user->email = 'not-an-email';

$errors = ValidationHandler::validate($user);

The handler preserves nested error structure for APIs and can return string messages for forms. No framework adapter is required.

Find your path

Build your first rule

Install Fynix and learn the v3 workflow in the introduction guide.

Use the public API

Learn Rule, RuleSet, the fluent API, and object validation in the public API reference.

Choose a validator

Find practical examples for every validator in the validator examples.

Copy a recipe

Start from a complete scenario in the validation recipes, from conditional fields to nested DTOs.