What language are needed to build a platform like typeform?

Question

typeform is an online form building, that Build beautiful, engaging, and conversational online forms, surveys, quizzes, landing pages, and much more.
this is the link www.typeform.com

Answer 1

HTML+CSS, JavaScript, Jquery, PHP, probably servlets, and whatever kind of database page uses (some use SQL, others mongo...), if I'm not mistaken. Oh, you'll likely need a bunch of different JS frameworks other than JQ (Specially for aesthetics and effects).
HTML5, learnt in-depth may also be more useful than plain HTML