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JSON Formatter

Format, validate, and explore JSON with a collapsible tree view — right in your browser.

Runs in your browserNo sign-up required
Input
Valid JSON · 13 keys · 16 values · 3 levels deep

The number 9007199254740993 is too long for JavaScript to hold exactly. This tool keeps it as written, but other apps may round it; store IDs like this as strings.

Output
{
"order_id":9007199254740993
"customer":{
"name":"Ravi Kumar"
"city":"Pune"
}
"items":[
0:{3 keys}
1:{3 keys}
]
"paid":true
"coupon":null
}
302 bytes formatted · 195 minified

More Than a Plain Formatter

Most JSON formatters do one thing — turn a single line of JSON into an indented block. This one adds an interactive tree view on top, so you can collapse and expand individual branches of a large or deeply nested object instead of scrolling through a wall of flat text, with each value type color-coded so structure is obvious at a glance. Format, minify, validate, and browse the structure, all in one place.

Useful for: backend and frontend developers debugging API responses, anyone editing a config file by hand, and students learning how JSON structure actually nests.

How to Use This Tool

  1. 1Paste your JSON or open a fileFrom an API response, a config file or a log. It is checked as you type.
  2. 2Pick 2-space, 4-space, or tab indentationWhichever matches your project's style.
  3. 3Fix any errorIf it isn't valid, you see the line, the column and what is wrong in plain words. Repair fixes common slips like trailing commas, single quotes, comments and Python True/None in one click.
  4. 4Switch between Tree and Text viewTree view lets you collapse and expand nested objects and arrays; Text view shows the raw formatted string.
  5. 5Copy or download the resultGrab the formatted JSON directly, or save it as a .json file.

Why the Tree View Actually Helps

  1. 1Collapse what you don't need to look atA deeply nested API response can be hundreds of lines formatted as plain text. The tree view lets you collapse entire branches down to a single line showing just the key count, so you can navigate straight to the part you actually care about.
  2. 2Color-coded value types at a glanceStrings, numbers, booleans, and null are each shown in a distinct color, so you can tell at a glance whether a field is the type you expected without reading every character.
  3. 3Catches structural mistakes a plain formatter would just rejectWhen JSON is invalid, this tool shows the line and column of the problem in plain words, and can repair common slips such as a trailing comma, an unquoted key or single quotes, instead of leaving you to scan the whole document.

Frequently Asked Questions

What does this JSON formatter do that a plain text formatter doesn't?

Beyond formatting and validating, it renders your JSON as an interactive, collapsible tree — so you can explore large or deeply nested structures without scrolling through hundreds of lines of flat text, and color-coding makes it easy to scan value types at a glance.

Why is my JSON showing as invalid?

The most common causes are a trailing comma after the last item, keys without double quotes, single quotes instead of double quotes, comments, or a missing comma between items. The tool shows the exact line and column with a ^ under the problem, and Repair can fix most of these for you. JSON copied from JavaScript or Python (True, False, None) is fixed too.

What's the difference between formatting and minifying?

Formatting adds indentation and line breaks to make JSON human-readable. Minifying strips all unnecessary whitespace to produce the smallest possible size — useful when sending JSON over a network where every byte matters, but not meant for reading.

Is my JSON data uploaded anywhere?

No. Checking, formatting and the tree view all run in your browser, and nothing you paste is sent to a server, so it is safe for API responses and internal data.

Why do long numbers like IDs change in other JSON formatters?

JavaScript can only hold whole numbers up to 9,007,199,254,740,991 exactly. Tools that use JSON.parse quietly round bigger numbers, so an ID like 9007199254740993 comes out as ...992. This formatter keeps every number exactly as you wrote it, and warns you when a number is that long so you can store it as a string.

What is "JSON inside a string"?

Logs and some APIs store JSON as an escaped string, like "{\"name\":\"Ravi\"}". The formatter spots this and offers Unwrap, which turns it back into readable JSON.

Can this tool handle very large JSON files?

Yes, within the limits of your browser's available memory — very large files (many megabytes) may render more slowly in tree view than in plain text view, since every node is interactive.

Is this JSON formatter free to use?

Yes, completely free, with no sign-up and no usage limit.