Survey JSON Schema Validator by SurveyJS

A backend service for validating SurveyJS JSON schemas and user responses. Use it to detect configuration errors in survey definitions and verify that collected responses conform to the corresponding survey schema.

Overview

The SurveyJS JSON Schema Validator helps you:

• Validate survey JSON schemas and detect structural, syntactic, and logical errors.
• Validate user responses against a survey schema, including required questions and data types.
• Catch issues early during development or before persisting survey data.

The service can be deployed as part of your backend infrastructure and exposed via a simple HTTP API.

Getting Started

Run the Service Locally

# Install dependencies
npm i
# Start the service in a Docker container
npm run dev

Once started, the service is available at http://localhost:3000.

Deploy with Docker

docker build -t surveyjs-json-schema-validator .
docker run -d -p 3000:3000 surveyjs-json-schema-validator

After deployment, the API is accessible at http://<host>:3000.

API Usage

Validate a Survey JSON Schema

To validate a survey JSON schema, send it in the body of a POST request to the /schema endpoint. If the schema is valid, the response contains an empty object. If validation fails, the response contains an object with an errors array describing the detected issues.

For example, the following request returns three errors:

• Unknown property someproperty
• Unknown variable somevariable used in an expression
• Missing required property name

const surveyJson = {
  "elements": [
    {
      "type": "text",
      "someproperty": true,
      "visibleIf": "{somevariable} = 1"
    }
  ]
};

fetch("http://localhost:3000/schema", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify(surveyJson),
})
  .then((response) => response.json())
  .then((data) => console.log(data))
  .catch((error) => console.error("Request failed:", error));

Validate a User Response

You can also validate a user response against a survey JSON schema. Send a POST request to the /response endpoint with the following payload:

• schema – The survey JSON schema.
• response – The user response object.

The service returns validation errors if the response does not satisfy the schema requirements. In the example below, the request returns a "Response required" error because the required q2 question is missing from the response.

const surveyJson = {
  "elements": [
    {
      "type": "text",
      "name": "q1",
      "isRequired": true
    },
    {
      "type": "text",
      "name": "q2",
      "isRequired": true
    }
  ]
};

const userResponse = {
  "q1": "Answer 1"
};

fetch("http://localhost:3000/response", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    schema: surveyJson,
    response: userResponse
  })
})
  .then((response) => response.json())
  .then((data) => console.log(data))
  .catch((error) => console.error("Request failed:", error));

Resources

• SurveyJS Website
• Documentation
• Live Examples
• What's New

Licensing

Survey JSON Schema Validator is distributed under the MIT license.