What is JSON?
JSON (JavaScript Object Notation) is a lightweight data-interchange format that is easy for humans to read and write, and easy for machines to parse and generate. Despite the name, JSON is language-independent — virtually every programming language can work with JSON.
Basic JSON Syntax
A JSON object is a collection of key-value pairs wrapped in curly braces:
{
"name": "Ravi Mehta",
"age": 28,
"city": "Surat",
"verified": true,
"score": 98.5,
"tags": ["developer", "designer"]
}JSON Data Types
JSON supports exactly six data types:
- String — text wrapped in double quotes: "hello"
- Number — integer or decimal: 42, 3.14
- Boolean — true or false
- Null — represents no value: null
- Object — key-value pairs: { "key": "value" }
- Array — ordered list: [1, 2, 3]
Why JSON is Used Everywhere
JSON became the standard for APIs because it is simpler than XML, smaller than YAML, and supported natively in JavaScript. When you call any modern REST API — whether Twitter, Stripe, or Google Maps — the response comes back as JSON.
Common JSON Mistakes
The most common JSON errors beginners make are: using single quotes instead of double quotes, adding trailing commas after the last item, and writing undefined (which is not a valid JSON value). Use JSONKit's validator to catch these instantly.
Tools to Work with JSON
JSONKit provides a full set of free browser-based tools for working with JSON:
- Format and beautify with the JSON Formatter
- Check for errors with the JSON Validator
- Compress with the JSON Minifier
- Convert to CSV, YAML or XML with the converters
- Compare two JSON objects with JSON Diff
- Decode JWT tokens with the JWT Decoder
All tools run entirely in your browser. Your data is never sent to any server.