BotDetect ASP.NET CAPTCHA Generator

BotDetect™ prevents automated submissions of ASP.NET forms using CAPTCHA images. The <BotDetect:Captcha> ASP.NET Custom Web Control and the Html.Captcha ASP.NET MVC Captcha helper generate and validate best-of-class Captcha images specifically designed to be out of reach of current computer vision and OCR technologies.

The controls also provide an audio Captcha alternative and keep ASP.NET web applications accessible to the visually impaired people for whom reading the Captcha code could be a problem, thus enabling you to make WCAG and Section 508 compliant websites.


BotDetect is unique among Captcha solutions in offering many Captcha image and sound styles. While each of them is easily comprehensible to human users, randomly using multiple Captcha generation algorithms 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.

Visual Studio 2015 & .NET 4.6 Ready

BotDetect ASP.NET CAPTCHA v3.0.16 supports the latest Microsoft Visual Studio 2015 and .NET 4.6 releases.

Full support for all Android & iOS devices

BotDetect ASP.NET CAPTCHA v3.0.13 audio now works on Android and iOS devices. Unlike other Captchas, sounds are played directly on the form page, without opening the media player app.

The BotDetect ASP.NET CAPTCHA Control

This high-security Captcha protection can be added to your ASP.NET forms using drag-and-drop in the Visual Studio designer, or fully customized and randomized in codebehind and web configuration files. The control may be installed with Nuget as well, and comes with a number of C# and VB.NET code examples demonstrating how to integrate Captcha protection in various ASP.NET usage scenarios, and how to use the many available Captcha features.

BotDetect ASP.NET CAPTCHA Features

BotDetect ASP.NET CAPTCHA Free Version

You can download BotDetect ASP.NET CAPTCHA Control for free and use it immediately! Your ASP.NET forms can be protected from spam (and bots in general) in minutes.

Keep in mind that we offer basic email support for free to all BotDetect users. So if you need any assistance integrating BotDetect or have any questions or feedback, our Support department is at your disposal.

Once the BotDetect Captcha control has been integrated into your ASP.NET application and you're satisfied with how it works, it's easy to upgrade your license if you need the extra features and options offered by commercial BotDetect versions.

BotDetect ASP.NET Captcha Free Download

BotDetect ASP.NET CAPTCHA System Requirements


Supported Operating Systems:

  • Windows 2016 Server
  • Windows 10
  • Windows 2012 Server R2
  • Windows 2012 Server
  • Windows 8
  • Windows 2008 Server R2
  • Windows 7
  • Windows 2008 Server
  • Windows Vista
  • Windows 2003 Server
  • Windows XP
  • Windows 2000 Server
  • Windows 2000 Professional

Supported Internet Information Services:

  • IIS 10
  • IIS 8.5
  • IIS 8.0
  • IIS 7.5
  • IIS 7.0
  • IIS 6.0
  • IIS 5.1
  • IIS 5.0

Supported .NET Framework versions:

  • .NET 4.6
  • .NET 4.5
  • .NET 4.0
  • .NET 3.5
  • .NET 3.0
  • .NET 2.0
  • .NET 1.1 (*)

* .NET 1.1 is supported by previous generation releases (BotDetect v2.0), which can be obtained on request.