Is there a JavaScript library for creating complex questionnaires?

Yes — there are several good JavaScript libraries for building complex questionnaires, depending on how much logic, validation, and UI control you need.

Popular options

• SurveyJS

  • Very popular for advanced surveys/questionnaires
  • Supports conditional logic, branching, validation, page breaks, calculated values, and custom question types
  • Works well with React, Angular, Vue, and plain JS
  • Good if you want a full-featured questionnaire engine

• Form.io

  • More of a form builder/platform than just a library
  • Strong for complex forms with conditional logic, data submission, workflows, and integrations
  • Useful if you need both front-end and back-end form handling

• React Hook Form + custom logic

  • Not a questionnaire library by itself, but good if you want to build a questionnaire in React with full control
  • You’d implement branching/logic yourself or with a schema layer

• Formik

  • Similar to React Hook Form, mostly for form state management
  • Better for general forms than highly dynamic questionnaires

• JSON Schema form libraries

  • Example: react-jsonschema-form / @rjsf/core
  • Good if your questionnaire can be described in JSON Schema
  • Can handle dynamic rendering, validation, and custom widgets

• WET-BOEW survey/form tools

  • More niche, but useful in specific government/accessibility contexts

Best fit for “complex questionnaires”

If you want something ready-made and powerful, SurveyJS is often the first one to look at.

What to look for

For complex questionnaires, check whether the library supports:

• branching / skip logic
• conditional visibility
• scoring or calculated fields
• multi-page flows
• validation rules
• custom question types
• saving/restoring progress
• export/import of questionnaire definitions

If you want, I can also recommend the best library based on your stack (React/Vue/plain JS) and the exact kind of questionnaire you’re building.