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

A) String

B) Array

C) Number

D) Date

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2. Which of the following is a common use of JSON in web development?

A) Compiling JavaScript code

B) Storing and exchanging data between client and server

C) Defining CSS styles

D) Rendering HTML elements

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3. Which JavaScript method can convert an object into a JSON string for an API request?

A) JSON.parse()

B) JSON.encode()

C) JSON.stringify()

D) JSON.serialize()

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4. What is a common vulnerability associated with parsing untrusted JSON?

A) JSON Brute Force

B) JSON Injection

C) JSON Parsing Loops

D) JSON Flooding

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5. How do you represent a null value in JSON?

A) NULL

B) (null)

C) "null"

D) null

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6. Which of these is a valid JSON object?

A) {name: "John", age: 30}

B) {name = "John"; age = 30}

C) [name: "John", age: 30]

D) {"name": "John", "age": 30}

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7. Which of these is NOT a valid JSON value?

A) A null value

B) A function

C) A boolean

D) A string

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8. How is JSON used in data interchange for machine learning models?

A) To serialize model configurations and results

B) To compile machine learning libraries

C) To train models directly

D) To render visualizations

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9. What is the purpose of the Authorization header in API requests?

A) To set request priority

B) To include authentication credentials

C) To specify the API version

D) To specify data format

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

A) Cross-Site Scripting (XSS)

B) Denial of Service (DoS)

C) SQL Injection

D) Remote Code Execution

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11. Which of the following is an example of a nested JSON object?

A) { "name": "John" }

B) { "person": { "name": "John", "age": 30 } }

C) { "name": "John", "age": 30 }

D) [ "John", 30 ]

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12. Which keyword is used to specify required fields in a JSON object?

A) fields

B) required

C) mandatory

D) include

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13. Can JSON keys have spaces?

A) No

B) Only in arrays

C) Yes, with quotes

D) Yes, without quotes

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14. What is the purpose of application/json MIME type?

A) To define JSON structure

B) To parse JSON

C) To identify JSON data format

D) To convert JSON to XML

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15. What is one method to detect changes in JSON data?

A) Using nested structures

B) Removing whitespace from JSON

C) Beautifying the JSON

D) Hashing the JSON content

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16. JSON is a strict subset of which language?

A) Python

B) SQL

C) XML

D) JavaScript

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

A) It makes JSON larger

B) It validates JSON schemas

C) It beautifies JSON responses

D) It encrypts JSON data in transit

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

A) Specifies a string pattern

B) Gives a short label to the schema or property

C) Sets a required field

D) Provides a description of the schema

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19. How does JSON.stringify() handle functions in objects?

A) Functions are converted to strings

B) Throws an error

C) Adds null in place of functions

D) Functions are ignored

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20. What symbol is used to enclose a JSON array?

A) []

B) ()

C) <>

D) {}

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21. What happens when duplicate keys are present in a JSON object?

A) Both key-value pairs are stored

B) The last key-value pair overrides the previous ones

C) An error is thrown

D) The first key-value pair is ignored

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22. How do you check if a string is valid JSON in JavaScript?

A) Use typeof to check its type

B) Parse it with JSON.parse() inside a try...catch block

C) Use JSON.isValid()

D) Use JSON.check()

23 / 30

23. Can a JSON object be empty?

A) Only when nested

B) No

C) Yes

D) Only in arrays

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24. What is a safe alternative to eval() for parsing JSON in JavaScript?

A) JSON.debug()

B) JSON.stringify()

C) JSON.minify()

D) JSON.parse()

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25. What does the enum keyword specify in JSON Schema?

A) The maximum length of a string

B) The format of a date field

C) A list of allowed values for a property

D) The default value of a property

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26. Which data structure is not directly supported by JSON?

A) Object

B) Array

C) String

D) Set

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27. JSON is _______________.

A) None of the above

B) Case-sensitive

C) Case-insensitive

D) Partially case-sensitive

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28. What is the use of the $ref keyword in JSON Schema?

A) To reference external files

B) To include reusable schema definitions

C) To define a default value

D) To specify required properties

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29. What does a JSON path debugger do?

A) Validates JSON syntax

B) Converts JSON to CSV

C) Extracts specific values from JSON

D) Beautifies JSON

30 / 30

30. What does the term API stand for?

A) Advanced Processing Interface

B) Application Process Integration

C) Automated Programming Integration

D) Application Programming Interface

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