JSON Basics Cheat Sheet

What is JSON?

• JSON stands for JavaScript Object Notation.
• It’s a lightweight, easy-to-read format used to store and exchange data.
• Both humans and computers can understand JSON easily.
• JSON is made up of key-value pairs organized inside curly braces {}.

Basic JSON Syntax

Element	Description	Example
Object	Unordered collection of key-value pairs.	{ "name": "Alice" }
Array	Ordered list of values.	[ "red", "green", "blue" ]
Key (Name)	Always a string in double quotes.	"age"
Value	Can be a string, number, object, array, true, false, or null.	"Alice", 30, true
String	Text wrapped in double quotes.	"hello world"
Number	Numeric value (integer or decimal).	42, 3.14
Boolean	true or false (no quotes).	true
Null	Represents empty or no value.	null

JSON Formatting Rules

• Data is inside curly braces {} for objects.
• Key-value pairs are separated by commas.
• Keys and string values are enclosed in double quotes "".
• Arrays use square brackets [].
• No trailing commas (commas after the last item) allowed.
• Whitespace and indentation are optional but improve readability.

Example: JSON Object

json{
  "name": "Alice",
  "age": 30,
  "is_student": false,
  "favorite_colors": ["red", "green", "blue"],
  "address": {
    "city": "New York",
    "zip_code": "10001"
  }
}

This JSON means:

• Name is “Alice”
• Age is 30
• Not a student
• Likes red, green, and blue colors
• Lives in New York, ZIP 10001

How to Read JSON

• Look for keys to understand what information is given.
• Values tell you the actual data.
• Arrays list multiple values in order.
• Nested objects group related data together.

Common JSON Use Cases

• Configuration files
• API responses
• Data exchange between web servers and clients
• Structured outputs from AI models like GPT-OSS-20B

Helpful Tips for Beginners

• Practice reading and writing simple JSON snippets.
• Use JSON viewers or text editors with JSON formatting support.
• Validate your JSON online with free tools like JSONLint.
• Remember keys must always be strings with double quotes.