Validation you can step through

Valiant Validation generates direct validators from compact, strongly typed rules. Author rules with fluent C#, model attributes, native branches, nested contexts, and reusable validators; then connect them to ASP.NET Core, OpenAPI, MediatR, or source-generated Mediator.

using Valiant.Validation;

[ValiantValidator]
public sealed partial class CreateUserValidator : ValidatorDefinition<CreateUser>
{
    public override void Configure(ValidationContext<CreateUser> context)
    {
        context.Property(user => user.Name)
            .Required()
            .MaxLength(64);

        context.Property(user => user.Age)
            .GreaterThanOrEqualTo(18);
    }
}

One rule model, several hosts

Layer	Integration
Domain/application	Inject `IValidator<T>` and call sync or async validation APIs
Minimal APIs	Add `.WithValiantValidation()` to a route
MVC	Register Valiant model validation globally
OpenAPI	Project generated rule metadata into schema constraints and `x-valiant-rules`
Messaging	Add a MediatR or Mediator pipeline behavior

Validation results preserve property paths, codes, messages, and severity. Errors invalidate the result; warnings and information remain available without making it invalid.

Documentation map

The sample catalog covers every selectable core and ASP.NET Core scenario. The same behaviors are covered by sample-focused tests, including WebApplicationFactory tests for every web sample.

One rule model, several hosts​

Documentation map​

One rule model, several hosts

Documentation map