Top 20 NuGet check Packages

Liquimail implements glue code to use Liquid templates with MailKit. This package contains ASP.NET Core extensions, helpers and components. For example, this package contains an health check which makes sure that SMTP server is reachable.
Very simple service that checks a VAT number returning whether or not the number is valid, the official company name and address when available using the EU web service
guard check assert
MVC4 integration for NotDeadYet.
ASPNetSpell - The Spell Checking library for Microsoft ASP.Net. This .Net Spellchecker supports MVC, C# and VB.Net. Features include: 
* A spellchecking library written in 100% pure .NET code. A complete user interface with plug-and-play support for ASP.Net web forms , AJAX and MVC Dictionari...
A simple way of exposing application health checks in .NET applications.
A toolkit for automatic updating of .NET applications from the web. It can be used as a simple deployment tool. Includes it's own executable updater, which is automatically downloaded the first time the application starts.
A simply arguments validation library with fluent API. Examples: Arg.NotNull(() => model); Arg.Validate(color, nameof(color)) .NotNullOrWhitespace() .LengthInRange(2, 20); // passangerCount is Nullable type Arg.IfNotNull(passan...
A version checker for an application
Simple helper methods for verifying argument values.
Lightweight Runtime-Only Contracts for .Net Standard 2.0. Focus lies on Readability and Extensibility. Under MIT License.
External dictionary source for Interface for VPKSoft.SpellCheckUtility and VPKSoft.ScintillaSpellCheck class libraries.
A robust and expressive condition-checking library
A .NET tool to check the validity of file and URL links in Markdown documents.
WebApi integration for NotDeadYet.
Ce package contient les assemblys satellites en français pour la bibliothèque MilNet.Web.Mvc.CheckBox
Common tools to create check boxes for ASP.NET Core MVC applications
Easy to use library for validating Polish NIP numbers: string nip = "8674068337"; bool isValid = Rychusoft.Validators.NipValidator.IsValid(nip);
.NET package to check the password strength of a certain passphrase. A password strength checker based from RegEx (Regulax Expression).