What is JSON? Complete Guide + Free Online Formatter

JSON (JavaScript Object Notation) is a lightweight data format used to store and exchange information between systems. If you've ever built a web app, called an API, or opened a config file — you've used JSON.

What Does JSON Look Like?

Here's a simple example:

{
  "name": "Mani",
  "age": 29,
  "city": "Atlanta",
  "skills": ["JavaScript", "Swift", "Python"]
}

Clean, readable, and universally understood by every programming language.

Why Does Formatting Matter?

Raw JSON from an API often looks like this:

{"name":"Mani","age":29,"city":"Atlanta","skills":["JavaScript","Swift","Python"]}

One long line. Hard to read, hard to debug. Formatting it adds proper indentation so you can instantly see the structure.

JSON Rules to Know

• Keys must be in double quotes
• Values can be strings, numbers, booleans, arrays, objects, or null
• No trailing commas
• No comments allowed

Common JSON Errors

• Missing comma between key-value pairs
• Trailing comma after the last item
• Single quotes instead of double quotes
• Unquoted keys — {name: "Mani"} is invalid

Format Your JSON Instantly

Stop squinting at minified JSON. Use our free JSON Formatter to beautify, validate, and fix your JSON in one click. No login. No upload to servers. 100% browser-based.

Paste your JSON → Click Format → Done.