BotDetect Ajax CAPTCHA Documentation

Ajax CAPTCHA in ASP.NET

• ASP.NET unobtrusive validation Ajax Captcha
• Get JSON Captcha validation result
• Captcha validation in partial form submission

There are several different approaches you can take when implementing Ajax Captcha validation of BotDetect ASP.NET Captcha, depending on your Ajax framework of choice and the amount and format of data exchanged by the client and server during Captcha validation through Ajax requests.

ASP.NET Unobtrusive Validation Ajax Captcha

BotDetect Captcha can be validated as part of ASP.NET unobtrusive validation of form fields in both ASP.NET MVC and ASP.NET WebForms applications. This approach to Ajax Captcha validation is shown in the ASP.NET MVC application template Captcha example and the ASP.NET WebForms application template Captcha example.

[back to top]

Getting the CAPTCHA Validation Result as JSON

If you prefer to handle the Ajax client-side workflow of Captcha validation yourself, you can make an Ajax request to the BotDetect Captcha handler validation end-point Url, available through the ValidationUrl property of the BotDetect client-side object.

For example, if you make an Ajax GET request to

FormCaptcha.ValidationUrl + "&i=" + userCaptchaCodeInput // TODO: read input

you will get the Captcha validation result as a simple true or false JSON value.

[back to top]

Partially Submitting the Form to Validate the CAPTCHA

If you prefer a custom Ajax implementation that submits the user Captcha code input to a custom end-point in your server-side ASP.NET code, you just need to ensure that you submit the CaptchaId and InstanceId values (available as Id and InstanceId properties of the BotDetect client-side object) along with the user input.

You can then get the Captcha validation result by passing these extra parameters to the static Validate() method of the BotDetect.Web.CaptchaControl class:

// TODO: add these values to the Ajax request on the client-side 
string userInput = Request.Params["userInput"] as string; 
string captchaId = Request.Params["captchaId"] as string; 
string instanceId = Request.Params["instanceId"] as string; 

bool isHuman = BotDetect.Web.Captcha.Validate(captchaId, userInput, 
  instanceId);

[back to top]

Ajax CAPTCHA in Java

• Get JSON Captcha validation result
• Captcha validation in partial form submission

There are several different approaches you can take when implementing Ajax Captcha validation of BotDetect Java Captcha, depending on your Ajax framework of choice and the amount and format of data exchanged by the client and server during Captcha validation through Ajax requests.

Getting the CAPTCHA Validation Result as JSON

If you prefer to handle the Ajax client-side workflow of Captcha validation yourself, you can make an Ajax request to the BotDetect Captcha handler validation end-point Url, available through the ValidationUrl property of the BotDetect client-side object.

For example, if you make an Ajax GET request to

formCaptcha.ValidationUrl + "&i=" + userCaptchaCodeInput // TODO: read input

you will get the Captcha validation result as a simple true or false JSON value.

[back to top]

Partially Submitting the Form to Validate the CAPTCHA

If you prefer a custom Ajax implementation that submits the user Captcha code input to a custom end-point in your server-side Java code, you just need to ensure that you submit the CaptchaId and InstanceId values (available as Id and InstanceId properties of the BotDetect client-side object) along with the user input.

You can then get the Captcha validation result by passing these extra parameters to the validate() method of the Captcha class:

// TODO: add these values to the Ajax request on the client-side 
String userInput = request.getParameter("userInput"); 
String captchaId = request.getParameter("captchaId"); 
String instanceId = request.getParameter("instanceId"); 

Captcha captcha = Captcha.load(request, captchaId); 
boolean isHuman = captcha.validate(userInput, instanceId); 

[back to top]

Ajax CAPTCHA in PHP

• Get JSON Captcha validation result
• Captcha validation in partial form submission

There are several different approaches you can take when implementing Ajax Captcha validation of BotDetect PHP Captcha, depending on your Ajax framework of choice and the amount and format of data exchanged by the client and server during Captcha validation through Ajax requests.

Getting the CAPTCHA Validation Result as JSON

If you prefer to handle the Ajax client-side workflow of Captcha validation yourself, you can make an Ajax request to the BotDetect Captcha handler validation end-point Url, available through the ValidationUrl property of the BotDetect client-side object.

For example, if you make an Ajax GET request to

FormCaptcha.ValidationUrl + "&i=" + userCaptchaCodeInput // TODO: read input

you will get the Captcha validation result as a simple true or false JSON value.

[back to top]

Partially Submitting the Form to Validate the CAPTCHA

If you prefer a custom Ajax implementation that submits the user Captcha code input to a custom end-point in your server-side PHP code, you just need to ensure that you submit the CaptchaId and InstanceId values (available as Id and InstanceId properties of the BotDetect client-side object) along with the user input.

You can then get the Captcha validation result by passing these extra parameters to the Validate() function of the Captcha class:

// TODO: add these values to the Ajax request on the client-side 
$userInput = $_REQUEST['userInput']; 
$captchaId = $_REQUEST['captchaId']; 
$instanceId = $_REQUEST['instanceId']; 

$ExampleCaptcha = new Captcha($captchaId); 
$isHuman = $ExampleCaptcha->Validate($userInput, $instanceId);

[back to top]