SurveyJS

[yusf]

Build fully-customizable surveys, forms and quizzes that seamlessly integrate into your application

https://surveyjs.io/

[msbt]

I've just integrated that on a website of mine - I don't think this would require to be a standalone app, you just include some js files and you're done, not sure what the benefit of a standalone version would be.

[yusf]

Did not know that. Thanks!