Inside and Out…

An attempt to understand technology better…

[WebService] CAPTCHA image generator for spam control

Posted by Gaurav Khanna on July 24, 2006

As part of the revamp efforts of, I have added the [Web]Services section where I have made available, for free use in your applications, various SOAP based services, built using the .NET Framework.

The first service I have added is a CAPTCHA image generation service. If you are running a website or a blog where you take input from the user in a HTML form, you would know about bots who can spam the form and send invalid details. One of the ways to handle this problem is challenge-response where you throw a challenge to the entity filling up the form and if their response is valid, only then the HTML form’s details are taken for subsequent processing.

One of the ways websites and various blog engines are trying to combat spam is by dynamically generating an image which shall containing a randomly generated text – and then prompting the user to enter the text. Only if there is a match, will the HTML form be processed.

The CAPTCHA image generation service can be used to generate this random text and create an image out of it, which can then be displayed on your webpage for verification. It is Basic Profile 1.1 specification compliant. Its free for use in your applications – you simply need to be registered with WinToolZone.

Complete service documentation is at


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