Free · Runs in your browser · No sign-up

JSON Formatter & Validator Online

Format, validate, beautify and minify JSON online for free.

Input JSON Drag & drop a .json file anywhere in this box

Formatted / Validated JSON

Your formatted JSON will appear here.

0 characters 0 lines 0 keys 0 objects 0 arrays

Privacy notice: your JSON data is processed locally in your browser and is never uploaded to a server.

What Is a JSON Formatter?

JSON (JavaScript Object Notation) is usually generated by an API, a database export, or a script, and it rarely comes out readable — everything sits on one line with no spacing. A JSON formatter takes that raw text and re-indents it, one property per line, nested objects and arrays stepped in from the level above, so the structure is visible at a glance instead of buried in a wall of characters. Formatting doesn't change the data itself; it only changes how it's displayed.

What Is a JSON Validator?

A JSON validator checks whether a piece of text actually follows JSON's syntax rules — matching brackets, quoted keys, no trailing commas, correctly escaped strings. If something is off, a good validator doesn't just say "invalid"; it points to roughly where the problem sits so you're not scanning the whole document by eye. This tool validates using your browser's own JSON parser, then translates the raw parser error into a plain-language explanation with an approximate line number.

How to Format JSON Online

Paste your JSON into the input box on the left, or use Upload JSON File / drag a .json file into the box.
Click Format JSON (or Beautify — they produce the same readable, indented output).
Read the result in the right-hand panel, with keys, strings, numbers and booleans colour-coded.
Use Copy JSON to copy the result, or Download JSON to save it as a .json file.

How to Validate JSON

Paste or upload your JSON, then click Validate JSON. If the JSON is well-formed you'll see a Valid JSON confirmation; if not, you'll get an Invalid JSON message along with the likely cause — a missing bracket, an unquoted key, or a trailing comma — and an approximate line number so you can jump straight to the problem instead of re-reading the whole file.

Common JSON Errors

Trailing commas — {"a":1,} is invalid; JSON does not allow a comma after the last item in an object or array.
Unquoted or single-quoted keys — keys must be wrapped in double quotes, e.g. {"name":"Ali"}, not {name:'Ali'}.
Missing closing brackets — every { needs a matching }, and every [ needs a matching ].
Unescaped quotes inside strings — a literal " inside a string value must be escaped as \".
Using undefined, comments, or trailing text — none of these are valid in standard JSON, unlike JavaScript object literals.

JSON Examples

Valid JSON

{
  "name": "Adnan",
  "age": 30,
  "skills": ["HTML", "CSS", "JavaScript"]
}

Invalid JSON (trailing comma)

{
  "name": "Adnan",
}

Nested JSON

{
  "user": {
    "name": "Adnan",
    "skills": ["HTML", "CSS", "JavaScript"]
  }
}

Array JSON

{
  "items": [1, 2, 3, 4]
}

JSON with boolean and null

{
  "active": true,
  "value": null
}

JSON Formatter Features

Format and beautify JSON with proper indentation.
Validate JSON with a plain-language error message and approximate line number.
Minify JSON by stripping unnecessary whitespace.
Load a sample JSON document to try the tool instantly.
Upload a .json file, or drag and drop it, straight into the editor.
Copy the result to your clipboard or download it as a .json file.
Live character, line, key, object and array counts.
Works on mobile, tablet and desktop — nothing is sent to a server.

How to Download Formatted JSON

After formatting or minifying, click Download JSON. Your browser saves the exact content shown in the output panel as formatted-data.json — the file is generated locally with no upload involved. For background on the JSON format itself, MDN's JSON reference documentation is a solid technical resource.

Frequently Asked Questions

What is a JSON Formatter?

A tool that re-indents raw JSON text so its structure — objects, arrays, keys and values — is easy to read.

What is a JSON Validator?

A tool that checks whether text follows valid JSON syntax and explains what's wrong when it doesn't.

Is this JSON Formatter free?

Yes. It's free to use, with no sign-up, no limits on how often you use it, and no account required.

Can I format JSON on mobile?

Yes. The layout stacks vertically on small screens and every button is sized for touch.

Is my JSON uploaded to a server?

No. Formatting, validating, minifying and file reading all happen locally in your browser's JavaScript engine.

Can I validate large JSON files?

Yes, within the limits of your browser's memory. Very large files (tens of megabytes) may be slower to process.

Can I download formatted JSON?

Yes, use the Download JSON button to save the current output as a .json file.

What does invalid JSON mean?

It means the text doesn't follow JSON syntax rules — commonly a trailing comma, missing bracket, or unquoted key.

What's the difference between formatting and validation?

Formatting changes how valid JSON looks (indentation and spacing). Validation checks whether the JSON is syntactically correct at all.

Can I use this tool without installing software?

Yes. It runs entirely in your web browser — nothing to install.

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Friday, August 14, 2026