JSON (JavaScript Object Notation) is a lightweight text format for storing and exchanging data. It's human-readable, language-independent, and used by virtually every web API to send data between a server and client.

What data types does JSON support?

JSON supports 6 data types: strings (in double quotes), numbers, booleans (true/false), null, arrays (ordered lists in []), and objects (key-value pairs in {}).

What is the difference between JSON and JavaScript objects?

JSON is a text format; a JavaScript object is a data structure in memory. JSON keys must be in double quotes (not single quotes). JSON cannot contain functions, undefined, or dates as native types.

How do I validate and format JSON?

Use PickConverter's free JSON Formatter at pickconverter.com/json-formatter. Paste your JSON to validate, beautify (with indentation), or minify it with one click.

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Developer Tools · 5 min read

What Is JSON? A Beginner's Guide to JSON Format

JSON is the universal language of web APIs. If your app talks to any online service, it almost certainly sends and receives JSON. Here's everything you need to know.

JSON Structure

JSON is built from two types of structures: objects (key-value pairs in curly braces) and arrays (ordered lists in square brackets).

{
  "name": "Alice",
  "age": 30,
  "active": true,
  "scores": [95, 87, 92],
  "address": {
    "city": "London",
    "zip": "EC1A 1BB"
  }
}

JSON Data Types

Type	Example
String	`"Hello, world!"`
Number	`42` or `3.14`
Boolean	`true` or `false`
Null	`null`
Array	`[1, "two", true]`
Object	`{"key": "value"}`

Common JSON Mistakes

Using single quotes instead of double quotes for keys or strings
Leaving a trailing comma after the last item in an object or array
Using undefined as a value (not supported in JSON)
Comments — JSON does not allow them (// comment will break parsing)

Frequently Asked Questions

A lightweight, human-readable text format for data storage and exchange. Used by virtually every web API.

Strings, numbers, booleans (true/false), null, arrays, and objects. No functions, undefineds, or native date types.

JSON requires double quotes on both keys and values. No functions, trailing commas, or comments allowed. JS objects are runtime structures; JSON is a text format.

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