ZeroAlloc.Validation

Source-generated, attribute-based validation for .NET that allocates nothing on the valid path. The source generator emits a strongly-typed validator class at build time — no reflection at runtime. When all rules pass, the entire validation cycle produces zero heap allocations.

Install

dotnet add package ZeroAlloc.Validation

30-Second Example

using ZeroAlloc.Validation;

[Validate]
public class CreateOrderRequest
{
    [NotEmpty][MaxLength(50)] public string  Reference { get; set; } = "";
    [GreaterThan(0)]          public decimal Amount    { get; set; }
    [NotEmpty][EmailAddress]  public string  Email     { get; set; } = "";
}

// The source generator emits CreateOrderRequestValidator at build time
var request   = new CreateOrderRequest
{
    Reference = "ORD-2026-001",
    Amount    = 99.99m,
    Email     = "customer@example.com"
};
var validator = new CreateOrderRequestValidator();
var result    = validator.Validate(request);

if (!result.IsValid)
    foreach (ref readonly var f in result.Failures)
        Console.WriteLine($"{f.PropertyName}: {f.ErrorMessage}");

Performance

Scenario	ZeroAlloc.Validation	FluentValidation	Speedup	Allocation (valid)
Flat model	6.7 ns	327 ns	~49×	0 B
Nested model	10.1 ns	619 ns	~61×	0 B
Collection (3×)	14.3 ns	2,043 ns	~143×	0 B

See Performance for full benchmark results.

Packages

Package	Purpose
ZeroAlloc.Validation	Core library — attributes, source generator, ValidationResult
ZeroAlloc.Validation.AspNetCore	Auto-validates request models; returns HTTP 422 on failure
ZeroAlloc.Validation.Inject	Emits AddZeroAllocValidators() — bulk DI registration in one call
ZeroAlloc.Validation.Options	Emits ValidateWithZeroAlloc() — plugs validators into Microsoft.Extensions.Options
ZeroAlloc.Validation.Testing	Fluent assertions for unit-testing validators

Features

• Zero heap allocation on the valid path
• 25+ built-in validation attributes
• Nested object and collection validation
• ASP.NET Core auto-validation (HTTP 422 on failure)
• Zero-friction DI registration (AddZeroAllocValidators())
• Source-generated Microsoft.Extensions.Options integration (ValidateWithZeroAlloc())
• Per-rule severity (Error, Warning, Info)
• Conditional rules (When / Unless / [SkipWhen])
• Short-circuit with [StopOnFirstFailure]
• Custom rules via [Must] predicates or [CustomValidation] methods
• Testing helpers via ZeroAlloc.Validation.Testing

Documentation

• Getting Started
• Attribute Reference
• Nested Validation
• Collection Validation
• Custom Validation
• Error Messages
• ASP.NET Core Integration
• DI Registration (Inject)
• Options Validation
• Testing
• Performance
• Advanced Features