Source Wireframe Kit - Library of 537 blocks for desktop and mobile prototyping
Typeform - Create beautiful, next-generation online forms with Typeform, the form & survey builder that makes asking questions easy & human on any device. Try it FREE!
Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
Survey Monkey - Create and publish online surveys in minutes, and view results graphically and in real time. SurveyMonkey provides free online questionnaire and survey software.
Platforma - Wireframe library of layouts and UI elements
Google Forms - Simple web forms from Google.