JSON Quiz Test Online (30 random Questions) 2026

This quick 30-minute challenge consists of 30 random multiple-choice questions designed to test your knowledge across various JSON topics, including the introduction to JSON, JSON syntax and basics, data types, operations in JavaScript, APIs and JSON, advanced structures, JSON Schema, tools and debugging, as well as performance and security considerations. Whether you’re new to JSON or looking to refine your skills, this quiz will enhance your understanding of JSON’s role in modern web development.

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30 Minutes JSON Quiz Test Online

Welcome to the JSON Quiz! This quick 30-minute challenge consists of 30 random multiple-choice questions designed to test your knowledge across various JSON topics, including the introduction to JSON, JSON syntax and basics, data types, operations in JavaScript, APIs and JSON, advanced structures, JSON Schema, tools and debugging, as well as performance and security considerations. Whether you're new to JSON or looking to refine your skills, this quiz will enhance your understanding of JSON's role in modern web development.

1 / 30

1. From which programming language is JSON derived?

A) C++

B) Java

C) Python

D) JavaScript

2 / 30

2. What does the title keyword do in JSON Schema?

A) Provides a description of the schema

B) Specifies a string pattern

C) Sets a required field

D) Gives a short label to the schema or property

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3. Which of the following best describes JSON?

A) A markup language like XML

B) A database system

C) A programming language

D) A lightweight data format

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4. Which attack can occur when JSON data is excessively large and causes resource exhaustion?

A) SQL Injection

B) Denial of Service (DoS)

C) Remote Code Execution

D) Cross-Site Scripting (XSS)

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5. How does HTTPS improve the security of JSON data transmission?

A) It beautifies JSON responses

B) It makes JSON larger

C) It encrypts JSON data in transit

D) It validates JSON schemas

6 / 30

6. In which cloud service is JSON commonly used for defining infrastructure as code?

A) Microsoft Azure

B) Amazon Web Services (AWS) CloudFormation

C) Firebase

D) DigitalOcean

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7. What does the Content-Security-Policy header do for JSON responses?

A) Specifies how JSON is cached

B) Ensures JSON is minified

C) Restricts where JSON can be loaded from to prevent cross-site scripting (XSS) attacks

D) Defines the format of JSON data

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8. Which JSON data type is used to represent a collection of items?

A) Number

B) Array

C) String

D) Object

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9. Which of the following is a valid JSON array?

A) (1, 2, 3)

B) {[1, 2, 3]}

C) [1, 2, 3]

D) <1, 2, 3>

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10. Which of the following is valid JSON for a mixed data type array?

A) [ { "name": "Alice" }, 25, "true" ]

B) All of the above

C) [ "Alice", 25, true ]

D) [ "Alice", "25", true ]

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11. Which of these techniques can prevent excessive JSON data exposure in APIs?

A) Avoiding nested JSON structures

B) Using JSON.stringify()

C) Compressing JSON

D) Enabling strict validation in APIs

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12. What is the primary role of JSON in GraphQL APIs?

A) To format query results

B) To handle authentication

C) To define the schema

D) To manage subscriptions

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13. What happens when a fetch() request encounters a network error?

A) Returns an empty object

B) Returns undefined

C) Throws a TypeError

D) Continues execution without errors

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14. What will be the output of the code: JSON.stringify({ key1: "value1", key2: function() { return "value2"; } });

A) Throws an error

B) {"key1": "value1", "key2": null}

C) {"key1": "value1"}

D) {"key1": "value1", "key2": "value2"}

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15. How can you validate JSON in a secure and efficient way?

A) Use a JSON Schema validator

B) Manually check the JSON

C) Use custom regular expressions

D) Ignore validation for trusted sources

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16. JSON is _______________.

A) Case-sensitive

B) None of the above

C) Case-insensitive

D) Partially case-sensitive

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17. What type of data does a JSON object contain?

A) Key-value pairs

B) Only text

C) Only numbers

D) Only arrays

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18. What does a JSON Formatter do?

A) Formats JSON into a readable and indented structure

B) Compresses JSON into a single line

C) Parses JSON into JavaScript objects

D) Converts JSON to XML

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19. How can you debug a failing JSON API request in a browser?

A) Check the network tab in developer tools

B) Validate the response JSON using a linter

C) All of the above

D) Use console.log for JSON output

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20. Which of the following is NOT a JSON data type?

A) Boolean

B) Null

C) Date

D) String

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21. What does a JSON array of objects look like?

A) [ { "key": "value" }, { "key": "value" } ]

B) { "array": [ "value1", "value2" ] }

C) { "object1": "value1", "object2": "value2" }

D) [ "object1", "object2" ]

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22. Which tool is used to validate JSON syntax?

A) JSONLint

B) JSONParser

C) Postman

D) XMLParser

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23. How can you format JSON output with spaces using JSON.stringify()?

A) Pass a null parameter to JSON.stringify()

B) Add a spaces property to the JSON object

C) Use JSON.prettyPrint()

D) Use the JSON.stringify(obj, null, 4) method

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24. Which of the following status codes indicates a successful API request?

A) 200

B) 404

C) 403

D) 500

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25. What does the Accept header specify in an API request?

A) The server's API version

B) The data format expected in the response

C) The client type

D) The authentication type

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26. What error does a missing comma between JSON key-value pairs produce?

A) Invalid JSON

B) SyntaxError: Unexpected token

C) Undefined object

D) Missing property name

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27. Which of the following ensures JSON data is safe from injection attacks?

A) Input validation and sanitization

B) Using only numeric data

C) Removing all keys from JSON

D) Minification

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28. What is used to enclose JSON keys?

A) No quotes

B) Parentheses

C) Single quotes

D) Double quotes

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29. Which type of JSON structure is most efficient for transmitting data?

A) JSON with comments

B) Deeply nested objects

C) Objects with arrays

D) Flat, simple key-value pairs

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30. What is the purpose of an API key in requests?

A) To encrypt the request data

B) To indicate the request priority

C) To authenticate the client

D) To specify the API version

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