There are many additional features of ClickFunnels. One of its most popular features is the built-in optin builder. It is easy to see how this feature can be very beneficial to most marketers. Optin builders take the kind of pre-written forms which can easily be prepared and written for you by a computer program. You might think that the idea of writing a whole lot of boring optin forms are beyond the capabilities of some average marketer, but the simple fact is that the built-in optin builder is capable of building hundreds if not thousands of open forms efficiently.