Wufoo is a web form builder. It allows you to build any kind of form and then either link people to it, or embed it right onto your own website (with full design control!)
I just had someone ask me for advice on undertaking the job of building a huge multi-page application form. It had to be secure. It had to ask questions and go to certain pages depending on how to answer other questions. It had to work on mobile. It had to have good UX and clear validation.
I told him the truth: Use Wufoo. Honest to god I wouldn't even dream of building that myself. It's not that I'm not capable, but it would be a boatload of work to get right and be difficult to maintain. I'd rather knock it out in an afternoon on Wufoo, have the end product be better, and have access to everything else awesome that Wufoo provides.