reCAPTCHA for .NET is one of the most popular and well-documented reCAPTCHA libraries used by thousands of .NET developers in their ASP.NET web forms and MVC applications. The library is created and maintained by Tanveer Yousuf.
To get started, go to http://recaptcha-net.mtd226.com.
If you find a bug in the library or you have an idea about a new feature, please try to search in the existing list of issues. If the bug or idea is not listed and addressed there, please open a new issue.