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NuGet · #56 most downloaded on NuGet
A validation library for .NET that uses a fluent interface to construct strongly-typed validation rules.
Last release 10 months ago
03 Dec 2025
Ships fairly regularly
a new release about every 2 months
Nearly every release is documented
notes for 58 of the last 60 stable releases
15 versions withdrawn
withdrawn after publishing
127 years old
191 releases · first in 1900
Resolved issue in AspNetCore integration where child collections were incorrectly validated by the ModelValidatorProvider
Resolved issue in AspNetCore integration where child collections were incorrectly validated by the ModelValidatorProvider
Added CancellationToken support to child validators
Added CancellationToken support to child validators
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One column per quarter.
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Introduce MessageFormatterFactory Additional language translations Additional checks to ensure HttpContext is registered
Introduce MessageFormatterFactory Additional language translations Additional checks to ensure HttpContext is registered
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Resolved issue where incorrect property name was generated when using RuleForEach combined with SetValidator Resolved an issue where nesting async val
Resolved issue where incorrect property name was generated when using RuleForEach combined with SetValidator Resolved an issue where nesting async validators inside DependentRules didn't wait for completion
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Added missing overload for WithMessage Ensure LanguageManager.Culture takes precedence over the current thread's culture
Added missing overload for WithMessage Ensure LanguageManager.Culture takes precedence over the current thread's culture
Various fixes to clientside validation in asp.net core
Various fixes to clientside validation in asp.net core
Improve message for MinimumLength and MaximumLength validators in English (other translations would be welcome). Added FluentValidationModelValidatorP
Improve message for MinimumLength and MaximumLength validators in English (other translations would be welcome). Added FluentValidationModelValidatorProvider.DisableDiscoveryOfPropertyValidators for backwards compatibility
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Resolve issue where the accessor cache would incorrectly cache certain expressions on method calls that return members Added the ability to disable th
Resolve issue where the accessor cache would incorrectly cache certain expressions on method calls that return members Added the ability to disable the accessor cache
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Fix DependentRules not working inside a top-level call to When Fix enum validator to work correctly with nullable enums
Fix DependentRules not working inside a top-level call to When Fix enum validator to work correctly with nullable enums
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Fix issue with TestHelper not using correct overload.
Fix issue with TestHelper not using correct overload.
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RegExValidator can now use a special {RegularExpression} placeholder in its error message. Fix two crashes when using the PCL build Fix issue with Get
RegExValidator can now use a special {RegularExpression} placeholder in its error message. Fix two crashes when using the PCL build Fix issue with GetAssembly
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