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JSON Formatter

Format, beautify, validate and minify JSON in your browser. Paste your JSON, choose your indentation and get readable output, or a clear explanation of what's wrong and where. Your JSON is processed in your browser and is not uploaded to Q3 Labs.

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  • · Helpful error messages

Private by design. Your JSON is processed in your browser and is not uploaded to Q3 Labs. It isn't stored, put in the URL, or sent to analytics.

0 characters

Up to 3,000,000 characters. Tip: press Ctrl+Enter (Cmd+Enter on Mac) to format.

Indentation

Validation & structure

Format, minify or validate some JSON to see whether it's valid and how it's structured.

Free JSON formatter online

JSON (JavaScript Object Notation) is the everyday format for sending data between servers, browsers and apps. APIs return it, configuration files use it and databases export it. Machines are happy with a single unbroken line, but people aren't, and one missing comma can be very hard to spot in a wall of text.

This tool does four things: it formats JSON so it's readable, validates it, minifies it when you need it compact, and lets you copy or download the result. It uses your browser's own JSON parser to decide what is valid, so the answer matches what JavaScript would do with your data.

How to format JSON

  1. Paste or type your JSON into the input box, or press Load Example to try it.
  2. Press Format JSON (or Ctrl+Enter). The indented result appears on the right.
  3. Choose an indentation: 2 spaces, 4 spaces or tabs. The result updates without changing your input.
  4. Copy or download the result with the buttons under the output.

How to beautify JSON

"Beautify", "pretty print" and "format" all mean the same thing here: adding line breaks and indentation so that each key, value and array item sits on its own line, indented to show how the data is nested. Beautifying changes only whitespace. Keys, values, order and even the way each number is written stay exactly as you entered them.

Beautified JSON is easier to read, easier to compare in a diff and easier to debug. That is why it is the usual form for configuration files and examples in documentation.

How to validate JSON

Press Validate JSON to check your text without producing output. If it is valid, you'll see its top-level type (object, array, string, number, boolean or null), the number of keys or items, how deeply it is nested, and counts of each kind of value.

If it is invalid, you'll see the parser's error message. Where your browser reports the position, the tool also shows the line and column, a few lines of your input with a marker, and a plain-English explanation for common mistakes. "Jump to error" selects that spot in your input. When a browser doesn't report a position, the tool says so instead of guessing.

Validation checks syntax only. It can't tell you whether the data is correct, complete or trustworthy.

How to minify JSON

Minifying removes every space, tab and line break that isn't part of a string. The result is the smallest text with the same meaning, which is useful for sending JSON over a network, embedding it in another file or storing it compactly. Whitespace inside strings is never touched. For a dedicated tool that also shows the size saved and lets you download the result, use the JSON Minifier.

JSON formatting example

These results are produced by the same code the tool above uses.

Minified input

{"name":"Eeshan","skills":["SEO","WordPress"],"active":true}

Formatted (2 spaces)

{
  "name": "Eeshan",
  "skills": [
    "SEO",
    "WordPress"
  ],
  "active": true
}

Minified again

{"name":"Eeshan","skills":["SEO","WordPress"],"active":true}

Common JSON syntax errors

Most invalid JSON comes down to a few recurring mistakes. Here they are with their fixes.

Common JSON syntax errors and how to fix them
InvalidFixedWhat went wrong
{"name": "Q3", "active": true,}{"name": "Q3", "active": true}Trailing comma. JSON doesn't allow a comma after the last item.
{'name': 'Q3'}{"name": "Q3"}Single quotes. Strings and names need double quotes.
{name: "Q3"}{"name": "Q3"}Unquoted property name. Names must be double-quoted strings.
{"a": 1 "b": 2}{"a": 1, "b": 2}Missing comma between two properties.
{"items": [1, 2, 3}{"items": [1, 2, 3]}Mismatched brackets. An array must close with ] before the object closes.
{"value": undefined}{"value": null}undefined, NaN and Infinity aren't JSON values. Use null or a number.
{"a": 1} // note{"a": 1}Comments aren't allowed in JSON.
{"text": "line 1 line 2"}{"text": "line 1\nline 2"}A raw line break inside a string. Write it as the escape \n.

JSON objects vs arrays

An object is a collection of named values in curly braces: {"name": "Q3 Labs", "active": true}. Each name is a string, and you look values up by name. Use an object when the data describes one thing with labelled properties.

An array is an ordered list in square brackets: ["SEO", "WordPress", "Ads"]. Items have positions rather than names. Use an array for a list of similar things. The two nest freely: an object can contain arrays, and arrays can contain objects, which is how most real API responses are shaped.

JSON data types

The six JSON value types
TypeExampleNotes
String"Q3 Labs"Text in double quotes. Special characters are escaped with a backslash, e.g. \n or \u00e9.
Number42, -3.14, 1.5e10No quotes. No leading zeros, no + sign, no NaN or Infinity.
Booleantrue, falseLower case, no quotes.
NullnullLower case, no quotes. Means "no value".
Object{"key": "value"}Unordered name/value pairs in curly braces. Names are strings.
Array[1, "two", null]An ordered list in square brackets, holding any values.

There is no date type, no undefined and no comments. Dates are normally sent as strings.

Why JSON formatting matters for developers

  • Debugging. Indented JSON makes structure visible, so you can see at a glance where a value sits.
  • Code review. Consistently formatted JSON gives clean diffs, so a change shows up as a change and not as a re-flowed file.
  • Finding mistakes. Line and column information turns "something is wrong somewhere" into a specific spot.
  • Payload size. Minified JSON is smaller to send, while formatted JSON is easier to read. You choose per use.

If you're building or integrating APIs, our web app development team and web development services work with JSON every day.

JSON formatter vs JSON validator

A validator answers one question: does this text follow JSON syntax? A formatter rewrites valid JSON so it reads well. In practice they go together, because a formatter can only re-indent JSON it can read, so it has to validate first. This tool shows both: Validate JSON reports the result and structure, and Format JSON gives you the layout.

Neither is the same as schema validation, which checks that the data has the fields and types an application expects. That needs a JSON Schema and different tooling. If you're adding structured data to a web page, our JSON-LD Schema Markup Generator builds and checks that kind of JSON for you.

Privacy and security

Your JSON is processed in your browser and is not uploaded to Q3 Labs. It isn't written to the URL or your browser's storage, and it is never sent to analytics. The tool treats what you paste purely as data: it is parsed, never executed, and values are shown as plain text, never as HTML.

As with any web page, avoid pasting live secrets such as production API keys or passwords on a shared or untrusted computer.

Frequently Asked Questions

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