Captcha 4.3.2

.NET Standard 1.6 .NET Framework 2.0
There is a newer version of this package available.
See the version list below for details.
Install-Package Captcha -Version 4.3.2
dotnet add package Captcha --version 4.3.2
<PackageReference Include="Captcha" Version="4.3.2" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add Captcha --version 4.3.2
The NuGet Team does not provide support for this client. Please contact its maintainers for support.
#r "nuget: Captcha, 4.3.2"
#r directive can be used in F# Interactive, C# scripting and .NET Interactive. Copy this into the interactive tool or source code of the script to reference the package.
// Install Captcha as a Cake Addin
#addin nuget:?package=Captcha&version=4.3.2

// Install Captcha as a Cake Tool
#tool nuget:?package=Captcha&version=4.3.2
The NuGet Team does not provide support for this client. Please contact its maintainers for support.

BotDetect CAPTCHA Generator protects ASP.NET (Core) forms from spam submissions. This secure and accessible Captcha protection is available on .NET (Core) for ASP.NET MVC 1-6 web applications, ASP.NET WebForms, and ASP.NET Web Pages. BotDetect works in China -- and it does not stalk you around 24/7.

BotDetect is unique among Captcha solutions by using many different image and sound algorithms for the generation  of Captcha codes. While each Captcha code algorithm is easily comprehensible to human users, generating Captcha codes by random algorithm makes the Captcha challenge practically impossible to pass automatically. This approach to Captcha security is validated by the BotDetect track record: we have over 3000 paying customers and not one confirmed case of automated Captcha breaking by spammers.
BotDetect provides an audio Captcha alternative to keep ASP.NET web applications accessible to the blind and other people for whom reading the Captcha code could be a problem, enabling you to make WCAG and Section 508 compliant websites.

 * 60 secure & readable Captcha image styles
 * 20 secure & accessible audio Captcha sound styles
 * Localized Captcha generation, using various Unicode character sets and downloadable multi-language sound pronunciations
 * Custom Captcha image size, format, color scheme...
 * Custom Captcha code length, style, character set, timeouts, generated code filtering...
 * Many other randomization & customization options
 * Produces XHTML 1.1 Strict, Section 508 and WCAG AAA compliant markup
 * Visual Studio .NET 2017, 2015, 2013, 2012, 2010, 2008, 2005 and 2003 Designer support
 * Medium trust environment support for shared servers
 * Fully compatible with ASP.NET Core 1.x and 2.0
 * Fully compatible with legacy .NET 2.0 and onwards, .NET Core 1.x and .NET Core 2.x
 * Fully compatible with ASP.NET Core MVC (MVC 6)
 * Fully compatible with ASP.NET MVC 1-5
 * Fully compatible with ASP.NET WebForms
 * Fully compatible with ASP.NET Web Pages
 * Fully compatible with ASP.NET Ajax and jQuery Ajax validation
 * Fully compatible with SharePoint Server / Foundation
 * Tested in Chrome, Firefox, Safari, IE, Edge and Opera browsers released since 2001.
 * Full support for all Android & iOS devices
 * It works in China
 * It does not stalk your users and visitors

What nuget to use?
Please note that from the version 4.2 onward we will have two BotDetect CAPTCHA nugets on the
* Use THIS nuget for ASP.NET applications running on the legacy .NET (non-Core) Frameworks
* Use THIS nuget for ASP.NET Core applications running on the .NET Core Frameworks -- from the BotDetect 4.3 onward
However, there is one special case that required the separate nuget.
 * Use our NEW helper nuget INSTEAD OF this one for the special case of ASP.NET Core applications running on the legacy .NET (non-Core) Frameworks -- this is available immediately. The new helper nuget name is and it is available at

Product Versions
.NET net5.0 net5.0-windows net6.0 net6.0-android net6.0-ios net6.0-maccatalyst net6.0-macos net6.0-tvos net6.0-windows
.NET Core netcoreapp1.0 netcoreapp1.1 netcoreapp2.0 netcoreapp2.1 netcoreapp2.2 netcoreapp3.0 netcoreapp3.1
.NET Standard netstandard1.6 netstandard2.0 netstandard2.1
.NET Framework net20 net35 net40 net403 net45 net451 net452 net46 net461 net462 net463 net47 net471 net472 net48
MonoAndroid monoandroid
MonoMac monomac
MonoTouch monotouch
Tizen tizen30 tizen40 tizen60
Xamarin.iOS xamarinios
Xamarin.Mac xamarinmac
Xamarin.TVOS xamarintvos
Xamarin.WatchOS xamarinwatchos
Compatible target framework(s)
Additional computed target framework(s)
Learn more about Target Frameworks and .NET Standard.

NuGet packages (2)

Showing the top 2 NuGet packages that depend on Captcha:

Package Downloads

EasyCaptcha library for Mvc


Contains common dependencies for Qore framework

GitHub repositories

This package is not used by any popular GitHub repositories.

Version Downloads Last updated
4.4.2 216,448 7/22/2019
4.4.1 10,644 4/8/2019
4.4.0 14,617 11/6/2018
4.3.3 9,970 10/23/2018
4.3.2 36,479 5/27/2018
4.3.1 5,590 5/14/2018
4.3.0 8,449 2/15/2018
4.2.0 54,805 4/29/2017
4.1.0 58,102 7/25/2016
4.0.1 19,014 3/9/2016
3.0.18 12,959 12/9/2015
3.0.17 5,373 10/22/2015
3.0.16 157,020 6/5/2014 2,393 4/24/2014
3.0.15 1,285 4/22/2014 8,694 2/17/2014 1,645 12/11/2013 1,145 12/9/2013 1,610 12/7/2013