JSON is everywhere — API responses, config files, database exports, logs. But raw JSON straight from a network request or production dump is often minified into a single unreadable line. A good JSON formatter turns that into structured, readable output in under a second.

What is JSON?

JSON (JavaScript Object Notation) is a lightweight text format for structured data. It uses key-value pairs, arrays, strings, numbers, booleans, and null — and it's the default data format for virtually every modern web API.

A valid JSON document is either an object ({ }) or an array ([ ]) at the top level. Everything inside follows strict syntax rules — which means one stray comma or unquoted key will break the entire document.

Why format JSON?

Minified JSON is compact but impossible to read at a glance:

{"user":{"id":42,"name":"Jane","roles":["admin","dev"],"active":true}}

Formatted, the same data becomes instantly scannable:

{
  "user": {
    "id": 42,
    "name": "Jane",
    "roles": ["admin", "dev"],
    "active": true
  }
}

Beyond readability, formatting also validates the JSON — if the formatter throws an error, you know there's a syntax problem before it crashes your app.

Common JSON errors and how to fix them

Trailing comma — {"a": 1,} is invalid JSON. Remove the comma before the closing brace or bracket.
Single quotes — JSON requires double quotes. {'key': 'value'} → {"key": "value"}
Unquoted keys — Unlike JavaScript objects, all JSON keys must be in double quotes. {key: 1} → {"key": 1}
Comments — Standard JSON does not support comments. Use JSONC or strip them before parsing.
Undefined / NaN / Infinity — These are JavaScript values, not valid JSON. Replace with null or a number string.

How to format JSON using inspectly.dev

Go to inspectly.dev/json
Paste your JSON into the input panel on the left
The formatter validates and beautifies it instantly — no button click needed
If there are errors, the error panel shows the exact line and a suggested fix
Use the Diff tab to compare two JSON documents side-by-side
Use the Schema tab to auto-detect the JSON Schema for your data

Everything runs in your browser. Your data is never sent to a server.

Tips for working with JSON

Path finder — click any value in the formatted output to copy its dot-notation path (e.g. user.roles[0]). Useful for writing selectors in code.
Auto-fix — the tool detects common issues like trailing commas and single quotes and offers a one-click fix.
Minify before sending — formatted JSON is larger. Use the minify option to reduce payload size for production API calls.
Word wrap — enable word wrap for long string values that exceed the panel width.

Frequently asked questions

Is it safe to paste sensitive JSON into an online formatter?

With inspectly.dev, yes — the tool runs entirely in your browser. Your JSON is processed locally using JavaScript and is never transmitted to any server. For extra caution with production secrets, use private browsing mode.

What's the difference between JSON and JavaScript objects?

JSON is a strict text format derived from JavaScript object syntax, but it's not the same thing. JSON requires double-quoted keys, doesn't allow trailing commas, comments, or undefined values, and must have a single root element. JavaScript objects are much more flexible.

Can I format very large JSON files?

Yes. The formatter handles large documents efficiently because all processing happens client-side in a fast JavaScript engine. Files up to several megabytes format without issues in modern browsers.

What is JSON Schema?

JSON Schema is a vocabulary for describing the structure of a JSON document — which fields are required, what types they must be, and what values are valid. The Schema tab in our formatter auto-generates a JSON Schema from your pasted data, which you can use for API documentation or validation libraries like Ajv or Zod.

Open JSON Formatter & Validator →