BotDetect ASP.NET & ASP.NET Core CAPTCHA Generator

Unlike Recaptcha the Stalker -- BotDetect CAPTCHA works in China! Licensable source-code; self-hosted -- doesn't stalk -- nor does it slurp your form-data! Think: GDPR & LGPD!

ASP.NET (Core) CAPTCHA Generator Highlights:

  • NATIONAL-SECURITY & PRIVACY FRIENDLY:
  • Self-hosted .NET Captcha Component -- no 3rd-party servers involved
  • Where having no 3rd-party servers involved also means:
    • no QUIC server-config/source-address-token & n-RTT session resumption
    • no TLS v1.3 PSK & n-RTT session resumption
    • no TLS v1.2 Session Ticket / Session ID session resumption
    • no cross-domain-shared TLS states
    • no TLS Channel IDs
    • no Token Binding
    • no old-school cookies-based ways of user identification and stalking
  • From a vendor that is not in the stalking business
    • nor a part of PRISM or XKeyscore
    • nor has anything to do with the NSA
  • Lets you never have 3rd-parties:
    • identify and stalk users on your site
    • slurp national-security-sensitive or privacy-sensitive form-data from your site
  • Plays nicely with Firefox, TOR Browser, and VPN users
  • NOTHING TO HIDE HERE:
  • Licensable source-code (C#/JavaScript) -- to fit neatly in your code audit processes
  • MULTINATIONALS FRIENDLY:
  • Works in China
  • Allows for EU GDPR and Brazilian LGPD compliant sites -- no need to risk those enormous multi-million dollar fines
  • 56 audio localizations (including all 24 official EU languages) let you treat each local market with that particular local market's familiar combination of script and language
  • EASY FRONTEND INTEGRATIONS:
  • Out-of-the-box integrations with various JavaScript frontends:
  • EASY BACKEND INTEGRATIONS:
  • Works in ASP.NET & ASP.NET Core 1/2 apps on top of .NET & .NET Core frameworks
  • SharePoint Feature for SharePoint Server / Foundation
  • DEVOPS FRIENDLY:
  • TestMode-enabled -- ready for your CI/CD pipelines
  • ACCESSIBLE:
  • Produces XHTML 1.1 Strict, Section 508 and WCAG AAA compliant markup
  • Accompanied with legible images and recognizable audios
  • MISCELLANEOUS:
  • 60 secure & readable Captcha image styles
  • 20 secure & accessible audio Captcha sound styles
  • Custom Captcha image size, code length, css & icons, tooltips, and pretty much everything else...
  • Full support for all major browsers and all Android & iOS devices

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ASP.NET CAPTCHA Generator -- NuGet Packages

The Enterprise Version nuget package is available in the nuget folder of the Enterprise Version archive.

The Free Version nuget packages, without the code examples, are available at nuget.org:

  • Use the Captcha nuget if you are running:
    • An ASP.NET Core application on top of a .NET Core framework, or
    • A legacy ASP.NET application on top of a legacy .NET framework
  • Use the CAPTCHA.asp.net.core.on.legacy.net.frameworks nuget if you are running:
    • An ASP.NET Core application on top of a legacy .NET framework

Below you will find how to download the C# and VB.NET code examples. They are free and will save you from succumbing to the common captcha implementation pitfalls. Grab them!

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ASP.NET CAPTCHA Generator -- Code Examples

The Free Version archive -- with the code examples -- can be downloaded from here.

The archive contains the following subfolders with code examples:

  • the core-on-core/examples/ -- ASP.NET Core apps on top of .NET Core frameworks
  • the core-on-lgcy/examples/ -- ASP.NET Core apps on top of legacy .NET frameworks
  • the lgcy-on-lgcy/examples/ -- Legacy ASP.NET apps on top of legacy .NET frameworks

All the examples are 'build and run-ready' Visual Studio projects.

With the code examples handy, your forms can be protected from spam in minutes!

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Reference the ASP.NET CAPTCHA Generator in Your Project

Run the following command in the Package Manager Console:

PM> Install-Package Captcha

After the command execution, the references to the BotDetect.dll, BotDetect.Web.Mvc.dll, and System.Data.SQLite.dll assemblies will be added to your project.

If your project does not use the MVC, the BotDetect.Web.Mvc.dll assembly reference can be safely removed from it.

If your project is not going to be using the Simple API, the System.Data.SQLite.dll assembly reference can be safely removed from it.

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Deploy Localized Audio .bdsp Packages

The ASP.NET CAPTCHA Generator has the en-US locale audio embedded. The .bdsp files for other locales are available at our Captcha localizations page.

Copy the downloaded .bdsp files for the locales you want to support to:

  • the BotDetectSounds subfolder of your app's root if you develop an ASP.NET Core app
  • the bin/BotDetectSounds subfolder of your app if you develop a legacy ASP.NET app

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Choose the Captcha API You Wish to Use:

BotDetect ASP.NET CAPTCHA Generator comes as a standalone Captcha library -- exposing two very different Captcha APIs. The overview of those Captcha APIs is here.

Note that those two APIs are like oil and water; they DO NOT mix at all -- use one or another!

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Traditional API

All of the Traditional API docs are here within your current navigation branch.

Your Traditional API integration should start at one of the following documentation sub-branches:

The Free Version archive contains the following Traditional API examples:

  • the core-on-core/examples/ -- ASP.NET Core on top of .NET Core
    • t_api-captcha-mvccore2-api_basics
    • t_api-captcha-mvccore2-aspnetcore.identity_scaffold
    • t_api-captcha-mvccore1-api_basics
    • t_api-captcha-mvccore1-aspnetcore.identity
  • the core-on-lgcy/examples/ -- ASP.NET Core on top of legacy .NET
    • t_api-captcha-mvccore2-api_basics
    • t_api-captcha-mvccore2-aspnetcore.identity_scaffold
    • t_api-captcha-mvccore1-api_basics
    • t_api-captcha-mvccore1-aspnetcore.identity
  • the lgcy-on-lgcy/examples/ -- Legacy ASP.NET on top of legacy .NET
    • t_api-captcha-mvc5-api_basics
    • t_api-captcha-mvc5-aspnet.identity
    • t_api-captcha-mvc5-aspnet.identity-spa
    • t_api-captcha-mvc4-api_basics
    • t_api-captcha-mvc4-web.security.membership
    • t_api-captcha-mvc3-web.security.membership
    • t_api-captcha-mvc2-web.security.membership
    • t_api-captcha-mvc1-web.security.membership
    • t_api-captcha-webforms-api_basics
    • t_api-captcha-webforms-api_basics-customvalidator
    • t_api-captcha-webforms-api_basics-msajax
    • t_api-captcha-webforms-api_basics-unobtrusive
    • t_api-captcha-webforms-aspnet.identity
    • t_api-captcha-webforms-web.security.membership
    • t_api-captcha-webpages-api_basics
    • t_api-captcha-webpages-web.security.membership
    • t_api-captcha~conf_via-app-config
    • t_api-captcha~conf_via-dynamic_config
    • t_api-captcha~conf_via-tag-config
    • t_api-captcha~demo
    • t_api-captcha~error-logging-log4net

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Simple API (Experimental)

We are reorganizing the Simple API docs. Until it is done please make sure that your Simple API integration efforts start with one of the following four step-by-step integration guides:

Those four guides are updated and polished and should be reasonably bug-free in this moment. If you find a bug, or would like to suggest an improvement, please let us know.

The rest of the Simple APIs docs is here.

The Free Version archive contains the following Simple API examples:

  • the core-on-core/examples/ -- ASP.NET Core on top of .NET Core
    • s_api-captcha-angular-webapi_mvccore1
    • s_api-captcha-angular-webapi_mvccore2
    • s_api-captcha-angularjs-webapi_mvccore1
    • s_api-captcha-angularjs-webapi_mvccore2
    • s_api-captcha-jquery-webapi_mvccore1
    • s_api-captcha-jquery-webapi_mvccore2
    • s_api-captcha-react-webapi_mvccore1
    • s_api-captcha-react-webapi_mvccore2
  • the core-on-lgcy/examples/ -- ASP.NET Core on top of legacy .NET
    • s_api-captcha-angular-webapi_mvccore1
    • s_api-captcha-angular-webapi_mvccore2
    • s_api-captcha-angularjs-webapi_mvccore1
    • s_api-captcha-angularjs-webapi_mvccore2
    • s_api-captcha-jquery-webapi_mvccore1
    • s_api-captcha-jquery-webapi_mvccore2
    • s_api-captcha-react-webapi_mvccore1
    • s_api-captcha-react-webapi_mvccore2
  • the lgcy-on-lgcy/examples/ -- Legacy ASP.NET on top of legacy .NET
    • s_api-captcha-angular-generic_handler
    • s_api-captcha-angular-webapi2
    • s_api-captcha-angularjs-generic_handler
    • s_api-captcha-angularjs-webapi2
    • s_api-captcha-jquery-generic_handler
    • s_api-captcha-jquery-webapi2
    • s_api-captcha-react-generic_handler
    • s_api-captcha-react-webapi2
    • s_api-captcha~error-logging-log4net

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Support & Upgrades

If you need any assistance integrating BotDetect or have any questions or feedback, our Support department is at your disposal.

Once the BotDetect Captcha generator 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.

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ASP.NET CAPTCHA Generator System Requirements

OS IIS .NET Browser

Supported Operating Systems:

  • Windows Server 2019
  • Windows Server 2016
  • Windows 10
  • Windows Server 2012 R2
  • Windows Server 2012
  • Windows 8
  • Windows Server 2008 R2
  • Windows 7
  • Windows Server 2008
  • Windows Vista
  • Windows Server 2003
  • Windows XP
  • Windows Server 2000
  • 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 Core 2.x
  • .NET Core 1.x
  • .NET 4.8
  • .NET 4.7
  • .NET 4.6
  • .NET 4.5
  • .NET 4.0
  • .NET 3.5
  • .NET 3.0
  • .NET 2.0

Officially Supported Browsers*:

  • Chrome 49+
  • Edge 20+
  • Firefox 52+
  • IE 8+
  • Opera 36+
  • Safari (OSX) 5+
  • Safari (iOS 6+)

Numerous other browsers are not officially supported but the captcha still works.

Read the notes below!
*

'Officially Supported Browsers' are those browsers for which we do the testing in order to ensure that both the image and audio captcha options are working properly.

Nonetheless, both the image and audio captcha options are working properly in the most of non-archaic ** browsers anyway -- officially-supported, or not -- while the image captcha option alone works in all of them!

If you find our 'Officially Supported Browsers' policy too-restrictive check Recaptcha the Stalker's one that says:

  • We support the two most recent major versions of the following:

    • desktop (Windows, Linux, Mac): Chrome, Firefox, Safari, IE

    • mobile: Chrome, Safari, Android native browser (4.0+)

We guess that after checking the Recaptcha's policy -- you will consider ours as the accommodative one :).

**

Archaic browsers?

At present, our 'Archaic Browsers' policy works this way:

  • Those last remaining few real humans still browsing around using the WinXP should update their browsers to the latest version that still works on the XP.

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© Captcha, Inc. 2004-2025. All rights reserved.

BotDetect, BotDetect CAPTCHA, Lanap, Lanap CAPTCHA, Lanap BotDetect, Lanap BotDetect CAPTCHA, Lanapsoft, Lanapsoft CAPTCHA, Lanapsoft BotDetect, Lanapsoft BotDetect CAPTCHA, and Lanap Software are trademarks of Captcha, Inc. All other product, brand, and company names are mentioned for identification purposes only and are trademarks or registered trademarks of their respective owners.

Captcha, Inc. -- formerly: Lanapsoft, Inc. / Lanap, Inc.