FluentValidation 12.1.1

Prefix Reserved
.NET 8.0 This package targets .NET 8.0. The package is compatible with this framework or higher. 
dotnet add package FluentValidation --version 12.1.1
                    


                    

                
NuGet\Install-Package FluentValidation -Version 12.1.1
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="12.1.1" />
For projects that support PackageReference, copy this XML node into the project file to reference the package. 
<PackageVersion Include="FluentValidation" Version="12.1.1" />
                    


                            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 12.1.1
                    


                    

                
#r "nuget: FluentValidation, 12.1.1"
#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@12.1.1
#: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=12.1.1
                    


                            Install as a Cake Addin
                        

                    

                
#tool nuget:?package=FluentValidation&version=12.1.1
                    


                            Install as a Cake Tool

FluentValidation is validation library for .NET that uses a fluent interface and lambda expressions for building strongly-typed validation rules.

Supporting the project

If you use FluentValidation in a commercial project, please sponsor the project financially. FluentValidation is developed and supported by @JeremySkinner for free in his spare time and financial sponsorship helps keep the project going. You can sponsor the project via either GitHub sponsors or OpenCollective.

Example

With FluentValidation, you can define a class that inherits from AbstractValidator which contains the rules for a particular class. The example below shows how you could define rules for a Customer class, and then how to execute the validator.

using FluentValidation;

public class CustomerValidator: AbstractValidator<Customer> {
  public CustomerValidator() {
    RuleFor(x => x.Surname).NotEmpty();
    RuleFor(x => x.Forename).NotEmpty().WithMessage("Please specify a first name");
    RuleFor(x => x.Discount).NotEqual(0).When(x => x.HasDiscount);
    RuleFor(x => x.Address).Length(20, 250);
    RuleFor(x => x.Postcode).Must(BeAValidPostcode).WithMessage("Please specify a valid postcode");
  }

  private bool BeAValidPostcode(string postcode) {
    // custom postcode validating logic goes here
  }
}

var customer = new Customer();
var validator = new CustomerValidator();

// Execute the validator.
ValidationResult results = validator.Validate(customer);

// Inspect any validation failures.
bool success = results.IsValid;
List<ValidationFailure> failures = results.Errors;

Full Documentation

Full documentation can be found at https://docs.fluentvalidation.net

Release Notes and Change Log

Release notes can be found on GitHub.

Product Compatible and additional computed target framework versions.
.NET net8.0 is compatible.  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. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

  • net8.0

    • No dependencies.

NuGet packages (3.0K)

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 (222)

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

Repository Stars
ardalis/CleanArchitecture
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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
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Windows tray utility / filesystem watcher / launcher for Syncthing
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.
FastEndpoints/FastEndpoints
A light-weight REST API development framework for ASP.NET 8 and newer.
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 1,975,886 12/3/2025
12.1.0 3,106,391 11/3/2025
12.0.0 24,036,926 5/5/2025
12.0.0-preview1 293,405 1/2/2025
11.12.0 469,526 11/3/2025
11.11.0 55,978,968 11/16/2024
11.10.0 22,693,832 9/15/2024
11.9.2 29,605,260 6/10/2024
11.9.1 15,118,751 4/23/2024
11.9.0 36,265,484 12/21/2023
11.8.1 10,468,769 11/22/2023
11.8.0 10,540,219 10/19/2023
11.7.1 12,679,271 8/12/2023
11.7.0 151,989 8/11/2023
11.6.0 9,680,356 7/4/2023
11.5.2 21,146,635 4/7/2023
11.5.1 72,695,867 2/20/2023
11.5.0 3,393,557 2/13/2023
11.4.0 20,878,140 11/23/2022
11.3.0 3,921,031 11/10/2022
11.2.2 17,781,890 9/11/2022
11.2.1 24,679,670 8/28/2022
11.2.0 8,011,800 8/8/2022
11.1.1 700,408 8/6/2022
11.1.0 14,025,174 6/22/2022
11.0.3 3,813,491 6/10/2022
11.0.2 5,845,274 5/27/2022
11.0.1 7,120,088 5/7/2022
11.0.0 7,436,955 4/30/2022
10.4.0 22,268,313 3/11/2022
10.3.6 28,642,694 12/13/2021
10.3.5 3,358,184 11/30/2021
10.3.4 10,783,075 10/22/2021
10.3.3 12,736,075 8/24/2021
10.3.1 764,354 8/19/2021
10.3.0 8,919,706 7/9/2021
10.2.3 8,919,178 6/3/2021
10.2.2 483,859 6/1/2021
10.2.1 1,409,465 5/30/2021
10.2.0 399,230 5/28/2021
10.1.0 5,769,301 4/28/2021
10.0.4 4,433,718 4/17/2021
9.5.4 8,102,276 4/5/2021
9.5.3 4,192,204 3/15/2021
9.5.2 2,105,438 3/8/2021
9.5.1 6,987,494 2/11/2021
9.5.0 3,552,929 1/31/2021
9.4.0 3,208,721 1/14/2021
9.3.0 15,454,316 11/10/2020
9.3.0-preview3 40,262 10/19/2020
9.3.0-preview2 156,063 9/15/2020
9.3.0-preview1 13,833 8/26/2020
9.2.2 7,373,868 9/20/2020
9.2.1 34,406 9/19/2020
9.2.0 8,302,007 8/26/2020
9.1.3 1,053,354 8/19/2020
9.1.2 1,005,801 8/12/2020
9.1.1 691,377 8/8/2020
9.1.0 338,521 8/8/2020
9.0.1 5,757,691 7/14/2020
9.0.0-preview5 91,028 5/23/2020
9.0.0-preview4 147,782 4/22/2020
9.0.0-preview3 211,144 2/29/2020
9.0.0-preview2 32,806 2/21/2020
9.0.0-preview1 102,166 2/8/2020
8.6.3 8,213,552 8/28/2020
8.6.2 29,932,422 2/29/2020
8.6.1 13,517,217 12/28/2019
8.6.0 4,468,872 12/4/2019
8.5.1 4,009,476 11/2/2019
8.5.0 6,843,057 9/24/2019
8.5.0-preview5 71,297 9/1/2019
8.5.0-preview4 103,979 7/23/2019
8.5.0-preview3 32,884 7/10/2019
8.5.0-preview2 90,928 6/13/2019
8.5.0-preview1 65,325 5/10/2019
8.4.0 15,341,443 5/10/2019
8.3.0 4,270,310 4/24/2019
8.2.3 757,205 4/12/2019
8.2.2 1,181,808 4/5/2019
8.2.1 511,158 4/4/2019
8.2.0 1,132,608 3/26/2019
8.1.3 5,277,936 1/25/2019
8.1.2 2,433,587 12/18/2018
8.1.1 627,782 12/11/2018
8.1.0 858,303 12/6/2018
8.1.0-preview2 29,997 11/14/2018
8.1.0-preview1 28,442 10/14/2018
8.0.101 974,762 11/24/2018
8.0.100 4,216,375 9/4/2018
8.0.0 1,210,806 8/16/2018
8.0.0-rc1 54,761 7/24/2018
8.0.0-preview4 26,211 7/16/2018
8.0.0-preview3 24,840 7/13/2018
8.0.0-preview2 24,681 7/13/2018
7.6.105 1,962,168 8/11/2018
7.6.104 2,852,830 7/6/2018
7.6.103 1,341,183 6/16/2018
7.6.102 347,686 6/14/2018
7.6.101 78,472 6/13/2018
7.6.100 183,549 6/7/2018
7.6.0 416,726 6/1/2018
7.6.0-preview1 53,797 4/12/2018
7.5.2 4,043,046 3/16/2018
7.5.1 287,044 3/11/2018
7.5.0 758,908 2/26/2018
7.4.0 2,469,145 1/26/2018
7.3.4 1,159,632 1/2/2018
7.3.3 201,949 12/22/2017
7.3.2 77,260 12/21/2017
7.3.1 354,247 12/13/2017
7.3.0 131,657 12/13/2017
7.3.0-beta3 28,705 12/8/2017
7.3.0-beta2 47,979 11/20/2017
7.3.0-beta1 25,513 11/11/2017
7.2.1 3,009,037 10/24/2017
7.2.0 859,551 10/5/2017
7.2.0-beta3 41,954 9/5/2017
7.2.0-beta2 27,784 8/22/2017
7.2.0-beta1 23,975 8/19/2017
7.1.1 2,514,526 7/25/2017
7.1.0 569,325 6/28/2017
7.1.0-beta1 23,751 6/24/2017
7.0.3 770,281 6/7/2017
7.0.2 294,887 5/26/2017
7.0.1 101,481 5/23/2017
7.0.0 772,160 5/19/2017
7.0.0-beta3 103,104 5/1/2017
7.0.0-beta2 27,449 4/17/2017
7.0.0-beta1 25,027 4/7/2017
6.4.1 2,407,303 3/15/2017
6.4.1-beta1 24,037 3/13/2017
6.4.0 1,107,029 3/3/2017
6.4.0-rc4 146,837 2/13/2017
6.4.0-rc3 39,994 2/3/2017
6.4.0-rc2 40,063 1/30/2017
6.4.0-rc1 23,851 1/30/2017
6.4.0-beta9 91,927 11/21/2016
6.4.0-beta8 50,854 10/31/2016
6.4.0-beta7 24,507 10/28/2016
6.4.0-beta6 24,794 10/25/2016
6.4.0-beta5 24,379 10/24/2016
6.4.0-beta4 24,486 10/21/2016
6.4.0-beta3 71,960 7/4/2016
6.4.0-beta2 25,365 7/1/2016
6.4.0-beta10 23,569 1/30/2017
6.4.0-beta1 28,782 6/28/2016
6.3.4-alpha 444,259 6/1/2016
6.3.3-alpha 23,362 5/27/2016
6.2.1 5,644,754 2/26/2016
6.2.1-beta1 28,839 2/24/2016
6.2.0 173,221 2/22/2016
6.2.0-beta1 24,690 2/12/2016
6.1.0 449,297 1/18/2016
6.0.2 119,293 1/5/2016
6.0.1 40,365 1/5/2016
6.0.0 137,508 12/22/2015
5.6.2 1,668,561 5/29/2015
5.6.1 35,190 5/29/2015
5.5.0 1,240,644 10/31/2014
5.4.0 617,583 7/3/2014
5.3.0 106,284 5/27/2014
5.2.0 77,872 5/21/2014
5.1.0 1,092,101 3/11/2014
5.0.0.1 575,628 10/24/2013
4.0.0.1 312,899 7/18/2013
4.0.0 122,962 4/29/2013
3.4.6 438,879 8/30/2012
3.4.0 73,565 8/17/2012
3.3.1 95,147 3/30/2012
3.2.0 79,714 11/14/2011
3.1.0 53,414 7/30/2011
3.0.0.1 26,644 7/5/2011
3.0.0 47,910 6/25/2011
2.0.0 78,904 1/9/2011
1.3.0 477,198 1/7/2011

FluentValidation 12 is a major release. Please read the upgrade guide at https://docs.fluentvalidation.net/en/latest/upgrading-to-12.html

Full release notes can be found at https://github.com/FluentValidation/FluentValidation/releases