We have created animation engines to render the CATPCHAs. Each engine offers a different kind of animation as you can see it under varieties. The engines were designed to be flexible so you can play with them by adjusting the rendering parameters. The constraints of the parameters are defined losely. In this way you are free to create new kinds of animations and play with them. Please, note that rendering an animation takes CPU time, so be patient while the system renders a new CATPCHA.

Each CAPTCHA engine has default settings for the parameters. The varieties menu usually contains the default look for an engine. The detail page of a CAPTCHA shows the different parametrizations of a CAPTCHA engine.  A parametrized engine is a CAPTCHA profile.