Formidable is imagined and realized at AMEOS.
It features smart template engine, many form widgets, ajax and events handling, XHTML valid code and accessibility thanks to the unobtrusive-js technique.
It is usable as pure TypoScript cObj, inside front end plugins or even in the TYPO3 backend.
New to Formidable : See our "quickstart guide".
You can also see the feature list of Formidable.