FluentValidation 9.0.0-preview4

Prefix Reserved
.NET Standard 2.0 This package targets .NET Standard 2.0. The package is compatible with this framework or higher. .NET Framework 4.6.1 This package targets .NET Framework 4.6.1. The package is compatible with this framework or higher.
This is a prerelease version of FluentValidation.
There is a newer version of this package available.
See the version list below for details. 
dotnet add package FluentValidation --version 9.0.0-preview4
                    


                    

                
NuGet\Install-Package FluentValidation -Version 9.0.0-preview4
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package. 
<PackageReference Include="FluentValidation" Version="9.0.0-preview4" />
For projects that support PackageReference, copy this XML node into the project file to reference the package. 
<PackageVersion Include="FluentValidation" Version="9.0.0-preview4" />
                    


                            Directory.Packages.props
                        

                    

                
<PackageReference Include="FluentValidation" />
                    


                            Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package. 
paket add FluentValidation --version 9.0.0-preview4
                    


                    

                
#r "nuget: FluentValidation, 9.0.0-preview4"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package. 
#:package FluentValidation@9.0.0-preview4
#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package. 
#addin nuget:?package=FluentValidation&version=9.0.0-preview4&prerelease
                    


                            Install as a Cake Addin
                        

                    

                
#tool nuget:?package=FluentValidation&version=9.0.0-preview4&prerelease
                    


                            Install as a Cake Tool

A validation library for .NET that uses a fluent interface to construct strongly-typed validation rules.

Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 was computed.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed.  net9.0 was computed.  net9.0-android was computed.  net9.0-browser was computed.  net9.0-ios was computed.  net9.0-maccatalyst was computed.  net9.0-macos was computed.  net9.0-tvos was computed.  net9.0-windows was computed.  net10.0 was computed.  net10.0-android was computed.  net10.0-browser was computed.  net10.0-ios was computed.  net10.0-maccatalyst was computed.  net10.0-macos was computed.  net10.0-tvos was computed.  net10.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 was computed. 
.NET Framework net461 is compatible.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

  • .NETFramework 4.6.1

    • No dependencies.

  • .NETStandard 2.0

    • No dependencies.

NuGet packages (2.9K)

Showing the top 5 NuGet packages that depend on FluentValidation:

Package Downloads
FluentValidation.DependencyInjectionExtensions

Dependency injection extensions for FluentValidation
FluentValidation.AspNetCore

AspNetCore integration for FluentValidation
Reo.Core.DataModels

Package Description
Ocelot

Ocelot is an API gateway based on .NET stack.
Reo.Core.Validation

Package Description

GitHub repositories (256)

Showing the top 20 popular GitHub repositories that depend on FluentValidation:

Repository Stars
ardalis/CleanArchitecture
Clean Architecture Solution Template: A proven Clean Architecture Template for ASP.NET Core 10
abpframework/abp
Open-source web application framework for ASP.NET Core! Offers an opinionated architecture to build enterprise software solutions with best practices on top of the .NET. Provides the fundamental infrastructure, cross-cutting-concern implementations, startup templates, application modules, UI themes, tooling and documentation.
kgrzybek/modular-monolith-with-ddd
Full Modular Monolith application with Domain-Driven Design approach.
Sonarr/Sonarr
Smart PVR for newsgroup and bittorrent users.
Radarr/Radarr
Movie organizer/manager for usenet and torrent users.
aspnetboilerplate/aspnetboilerplate
ASP.NET Boilerplate - Web Application Framework
dotnet-architecture/eShopOnWeb
Sample ASP.NET Core 8.0 reference application, now community supported: https://github.com/NimblePros/eShopOnWeb
MudBlazor/MudBlazor
Blazor Component Library based on Material Design principles with an emphasis on ease of use and extensibility
ThreeMammals/Ocelot
.NET API Gateway
NancyFx/Nancy
Lightweight, low-ceremony, framework for building HTTP based services on .Net and Mono
EduardoPires/EquinoxProject
Web Application ASP.NET 9 using Clean Architecture, DDD, CQRS, Event Sourcing and a lot of good practices
canton7/SyncTrayzor
Windows tray utility / filesystem watcher / launcher for Syncthing
FastEndpoints/FastEndpoints
A light-weight REST API development framework for ASP.NET 8 and newer.
Prowlarr/Prowlarr
Prowlarr is an indexer manager/proxy built on the popular *arr .net/reactjs base stack to integrate with your various PVR apps, supporting management of both Torrent Trackers and Usenet Indexers.
jasontaylordev/NorthwindTraders
Northwind Traders is a sample application built using ASP.NET Core and Entity Framework Core.
Lidarr/Lidarr
Looks and smells like Sonarr but made for music.
microsoft/RulesEngine
A fast and reliable .NET Rules Engine with extensive Dynamic expression support
fullstackhero/blazor-starter-kit
Clean Architecture Template for Blazor WebAssembly Built with MudBlazor Components.
Megabit/Blazorise
Blazorise is a component library built on top of Blazor with support for CSS frameworks like Bootstrap, Tailwind, Bulma, AntDesign, and Material.
Readarr/Readarr
Book Manager and Automation (Sonarr for Ebooks)
Version Downloads Last Updated
12.1.1 32,006 12/3/2025
12.1.0 1,696,883 11/3/2025
12.0.0 20,489,218 5/5/2025
12.0.0-preview1 264,611 1/2/2025
11.12.0 164,668 11/3/2025
11.11.0 50,457,888 11/16/2024
11.10.0 21,516,158 9/15/2024
11.9.2 28,325,452 6/10/2024
11.9.1 14,479,208 4/23/2024
11.9.0 34,958,229 12/21/2023
11.8.1 10,098,495 11/22/2023
11.8.0 10,204,710 10/19/2023
11.7.1 12,339,686 8/12/2023
11.7.0 146,826 8/11/2023
11.6.0 9,415,968 7/4/2023
11.5.2 20,670,837 4/7/2023
11.5.1 69,869,185 2/20/2023
11.5.0 3,271,372 2/13/2023
11.4.0 20,481,014 11/23/2022
11.3.0 3,842,207 11/10/2022
11.2.2 17,439,865 9/11/2022
11.2.1 24,287,528 8/28/2022
11.2.0 7,942,527 8/8/2022
11.1.1 689,890 8/6/2022
11.1.0 13,818,889 6/22/2022
11.0.3 3,756,001 6/10/2022
11.0.2 5,725,782 5/27/2022
11.0.1 7,035,380 5/7/2022
11.0.0 7,186,928 4/30/2022
10.4.0 21,875,342 3/11/2022
10.3.6 28,325,553 12/13/2021
10.3.5 3,327,867 11/30/2021
10.3.4 10,668,540 10/22/2021
10.3.3 12,599,195 8/24/2021
10.3.1 758,599 8/19/2021
10.3.0 8,807,063 7/9/2021
10.2.3 8,821,458 6/3/2021
10.2.2 479,559 6/1/2021
10.2.1 1,400,625 5/30/2021
10.2.0 396,538 5/28/2021
10.1.0 5,687,503 4/28/2021
10.0.4 4,407,346 4/17/2021
9.5.4 7,799,972 4/5/2021
9.5.3 4,162,737 3/15/2021
9.5.2 2,081,469 3/8/2021
9.5.1 6,947,498 2/11/2021
9.5.0 3,517,202 1/31/2021
9.4.0 3,183,373 1/14/2021
9.3.0 15,341,477 11/10/2020
9.3.0-preview3 40,140 10/19/2020
9.3.0-preview2 155,003 9/15/2020
9.3.0-preview1 13,714 8/26/2020
9.2.2 7,334,605 9/20/2020
9.2.1 33,939 9/19/2020
9.2.0 8,187,970 8/26/2020
9.1.3 1,049,393 8/19/2020
9.1.2 996,754 8/12/2020
9.1.1 688,843 8/8/2020
9.1.0 326,128 8/8/2020
9.0.1 5,720,644 7/14/2020
9.0.0-preview5 90,759 5/23/2020
9.0.0-preview4 147,636 4/22/2020
9.0.0-preview3 209,604 2/29/2020
9.0.0-preview2 32,745 2/21/2020
9.0.0-preview1 101,643 2/8/2020
8.6.3 8,061,124 8/28/2020
8.6.2 29,669,115 2/29/2020
8.6.1 13,399,349 12/28/2019
8.6.0 4,434,162 12/4/2019
8.5.1 3,975,608 11/2/2019
8.5.0 6,782,873 9/24/2019
8.5.0-preview5 71,048 9/1/2019
8.5.0-preview4 103,482 7/23/2019
8.5.0-preview3 32,847 7/10/2019
8.5.0-preview2 89,961 6/13/2019
8.5.0-preview1 64,870 5/10/2019
8.4.0 15,197,452 5/10/2019
8.3.0 4,237,894 4/24/2019
8.2.3 748,291 4/12/2019
8.2.2 1,160,916 4/5/2019
8.2.1 508,318 4/4/2019
8.2.0 1,119,312 3/26/2019
8.1.3 5,257,270 1/25/2019
8.1.2 2,421,327 12/18/2018
8.1.1 623,889 12/11/2018
8.1.0 855,375 12/6/2018
8.1.0-preview2 29,952 11/14/2018
8.1.0-preview1 28,279 10/14/2018
8.0.101 967,745 11/24/2018
8.0.100 4,188,691 9/4/2018
8.0.0 1,190,820 8/16/2018
8.0.0-rc1 54,650 7/24/2018
8.0.0-preview4 26,164 7/16/2018
8.0.0-preview3 24,779 7/13/2018
8.0.0-preview2 24,629 7/13/2018
7.6.105 1,922,555 8/11/2018
7.6.104 2,843,116 7/6/2018
7.6.103 1,335,116 6/16/2018
7.6.102 345,768 6/14/2018
7.6.101 78,274 6/13/2018
7.6.100 182,232 6/7/2018
7.6.0 413,787 6/1/2018
7.6.0-preview1 53,365 4/12/2018
7.5.2 4,023,904 3/16/2018
7.5.1 284,523 3/11/2018
7.5.0 757,766 2/26/2018
7.4.0 2,420,222 1/26/2018
7.3.4 1,149,346 1/2/2018
7.3.3 200,724 12/22/2017
7.3.2 77,076 12/21/2017
7.3.1 352,011 12/13/2017
7.3.0 129,475 12/13/2017
7.3.0-beta3 28,649 12/8/2017
7.3.0-beta2 47,795 11/20/2017
7.3.0-beta1 25,465 11/11/2017
7.2.1 2,986,450 10/24/2017
7.2.0 855,823 10/5/2017
7.2.0-beta3 41,913 9/5/2017
7.2.0-beta2 27,738 8/22/2017
7.2.0-beta1 23,932 8/19/2017
7.1.1 2,456,579 7/25/2017
7.1.0 566,737 6/28/2017
7.1.0-beta1 23,712 6/24/2017
7.0.3 767,700 6/7/2017
7.0.2 293,464 5/26/2017
7.0.1 100,271 5/23/2017
7.0.0 765,007 5/19/2017
7.0.0-beta3 83,115 5/1/2017
7.0.0-beta2 27,391 4/17/2017
7.0.0-beta1 24,982 4/7/2017
6.4.1 2,302,433 3/15/2017
6.4.1-beta1 23,999 3/13/2017
6.4.0 1,088,627 3/3/2017
6.4.0-rc4 146,779 2/13/2017
6.4.0-rc3 39,950 2/3/2017
6.4.0-rc2 40,013 1/30/2017
6.4.0-rc1 23,806 1/30/2017
6.4.0-beta9 91,842 11/21/2016
6.4.0-beta8 50,808 10/31/2016
6.4.0-beta7 24,460 10/28/2016
6.4.0-beta6 24,748 10/25/2016
6.4.0-beta5 24,324 10/24/2016
6.4.0-beta4 24,426 10/21/2016
6.4.0-beta3 71,831 7/4/2016
6.4.0-beta2 25,319 7/1/2016
6.4.0-beta10 23,518 1/30/2017
6.4.0-beta1 28,730 6/28/2016
6.3.4-alpha 438,642 6/1/2016
6.3.3-alpha 23,315 5/27/2016
6.2.1 5,593,001 2/26/2016
6.2.1-beta1 28,793 2/24/2016
6.2.0 172,894 2/22/2016
6.2.0-beta1 24,643 2/12/2016
6.1.0 444,334 1/18/2016
6.0.2 118,728 1/5/2016
6.0.1 40,294 1/5/2016
6.0.0 136,679 12/22/2015
5.6.2 1,652,418 5/29/2015
5.6.1 35,107 5/29/2015
5.5.0 1,234,116 10/31/2014
5.4.0 615,590 7/3/2014
5.3.0 106,140 5/27/2014
5.2.0 77,469 5/21/2014
5.1.0 1,082,265 3/11/2014
5.0.0.1 569,696 10/24/2013
4.0.0.1 310,808 7/18/2013
4.0.0 121,935 4/29/2013
3.4.6 435,398 8/30/2012
3.4.0 72,862 8/17/2012
3.3.1 94,489 3/30/2012
3.2.0 79,314 11/14/2011
3.1.0 53,341 7/30/2011
3.0.0.1 26,588 7/5/2011
3.0.0 47,725 6/25/2011
2.0.0 78,315 1/9/2011
1.3.0 454,966 1/7/2011

FluentValidation 9 is a major release. Please read the upgrade notes at https://docs.fluentvalidation.net/en/latest/upgrading-to-9.html

Changes in 9.0.0:
* Removed support for netstandard1.1 and netstandard1.6
* Removed support for end-of-life .NET Core versions (2.2 and 3.0). LTS versions are supported (2.1 and 3.1)
* Default email validation mode now uses the same logic as ASP.NET Core. Previous regex behaviour is opt-in.
* TestHelper advanced mode now has more features (see https://docs.fluentvalidation.net/en/latest/testing.html#advanced-test-extensions)
* Equal/NotEqual now perform ordinal comparison when used with string properties
* Severity can now be set dynamically with a callback
* Removed WithLocalizedMessage (WithMessage that takes a callback is the replacement)
* Removed ResourceName from ValidationFailure
* Removed ResourceName and ResourceType from IStringSource.
* Removed SetCollectionValidator which was deprecated in 8.0
* Additional overload of OnAnyFailure that can receive a collection of validation failures
* Remove DisplayAttribute integration and reference to DataAnnotations.
* ComparisonProperty placeholder is now formatted like PropertyName
* Translations of default error messages into other languages are now lazily-loaded
* Added Slovenian translations of default error messages.
* Added Icelandic translations of default error messages.
* Added WithMessageArgument to the test helpers.
* Add additional overload of SetValidator that takes a Func that receives the current property value.
* ASP.NET Core: FluentValidationModelValidatorProvider and FluentValidationModelValidator are now public.
* Work around a bug in ASP.NET Core's integration testing components that can cause ConfigureServices to run multiple times.
* SourceLink integration.
* {CollectionIndex} placeholder can now be accessed in child validators.
* Additional ValidationException constructor that allows using both the default message and a custom one together.
* ScalePrecisionValidator algorithm now matches SQL Server.
* Additional overload of the When methods that contain the validation context.

Full release notes can be found at https://github.com/FluentValidation/FluentValidation/blob/master/Changelog.txt