JSON Formatter
Format, validate, minify and beautify JSON instantly.
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How To Use
Paste your JSON
into the Input JSON editor or upload a .json or .txt file containing valid JSON.
Choose an action
Format to beautify, Validate to check syntax, or Minify to compress.
Review the result
in the Output JSON editor.
Copy the result
to your clipboard or download it as a .json or .txt file.
If the JSON is invalid
the formatter displays the parsing error along with helpful hints for common mistakes.
About JSON Formatter
The DevToolVerse JSON Formatter helps you format, validate, and minify JSON instantly in your browser. Whether you're debugging an API response, inspecting configuration files, or working with large JSON documents, the formatter makes your data easier to read and verify.
All processing happens locally in your browser, meaning your JSON is never uploaded to a server. This keeps your data private while providing fast formatting, validation, and minification.
Developers reach for a JSON formatter in a few recurring situations: reading a minified API response returned by a REST endpoint, inspecting the payload of an incoming webhook or request body, checking a configuration file such as package.json or tsconfig.json for a syntax mistake, or simply making a JSON blob readable before pasting it into documentation or a bug report. If you need to compare two versions of a JSON document — for example, before and after an API change — the JSON Diff tool highlights exactly what changed. And if you're working with a JSON Web Token, keep in mind its payload is itself a JSON object once decoded — the JWT Decoder can decode and display it directly.
Before (minified)
{"id":101,"name":"Wireless Mouse","inStock":true,"tags":["electronics","accessories"],"price":24.99}After (formatted)
{
"id": 101,
"name": "Wireless Mouse",
"inStock": true,
"tags": [
"electronics",
"accessories"
],
"price": 24.99
}Features
Beautify JSON
with clean and consistent indentation.
Validate JSON
and quickly identify syntax errors.
Minify JSON
by removing unnecessary whitespace.
Upload JSON or TXT files
for quick editing.
Copy formatted output
to your clipboard with one click.
Download formatted JSON
as .json or .txt.
Automatic statistics
including character count, line count, object count, array count, nesting depth and file size.
Helpful error hints
for common JSON mistakes.
Runs entirely in your browser
your data never leaves your device.
Quick Reference
The six JSON data types, plus the syntax rules the formatter and validator enforce.
| Type | Example | Description |
|---|---|---|
| Object | { "key": "value" } | An unordered set of key/value pairs. Keys must be strings. |
| Array | [1, 2, 3] | An ordered list of values, which can be any valid JSON type. |
| String | "hello" | Text wrapped in double quotes. |
| Number | 42, -3.14 | Integer or floating-point. No leading zeros. |
| Boolean | true, false | Lowercase only — True and False are not valid JSON. |
| null | null | Represents an empty or missing value. undefined is not valid JSON. |
- Property names and string values must use double quotes ("), never single quotes.
- A trailing comma after the last item in an object or array is not allowed.
- JSON has no comment syntax — // and /* */ are not valid.
- Booleans must be lowercase true or false, and empty values must be null.
Common JSON Mistakes
Trailing Commas
A comma left after the last property or array item is invalid in standard JSON — remove it.
✗ { "a": 1, "b": 2, }✓ { "a": 1, "b": 2 }Single Quotes
JSON requires double quotes for property names and string values. Single quotes will fail to parse.
✗ { 'name': 'value' }✓ { "name": "value" }Unquoted Property Names
Unlike a plain JavaScript object literal, every JSON property name must be wrapped in double quotes.
✗ { name: "value" }✓ { "name": "value" }Missing Closing Braces/Brackets
Every { and [ needs a matching closing } or ] — an unbalanced pair typically causes an "unexpected end of input" error.
✗ { "a": [1, 2, 3 }✓ { "a": [1, 2, 3] }Comments Inside JSON
JSON has no comment syntax. // and /* */ must be removed before it will parse.
✗ { "a": 1 /* note */ }✓ { "a": 1 }Duplicate Keys
Duplicate keys don't cause a parse error, but most parsers silently keep only the last value — avoid them entirely.
✗ { "id": 1, "id": 2 }✓ { "id": 2 }Limitations & Important Notes
- JSON does not support comments — // and /* */ will cause a parse error.
- Trailing commas after the last item in an object or array are not allowed.
- JSON requires double quotes for strings and property names; JavaScript-style single quotes are invalid.
- Duplicate keys don't cause an error, but only the last value is typically kept, so they should generally be avoided.
- Very large JSON documents are limited by your browser and device memory, since all processing happens locally.
FAQ
JSON (JavaScript Object Notation) is a lightweight data-interchange format commonly used by APIs and applications to exchange structured data.
Yes. The JSON Formatter is completely free to use with no registration required.
No. Everything is processed locally in your browser. Your JSON is never uploaded to any server.
Yes. Large JSON files can be formatted directly in your browser. Performance depends on your device and browser.
Format adds indentation and spacing to improve readability, while Minify removes unnecessary whitespace to reduce file size.
Common causes include using single quotes instead of double quotes, missing commas, trailing commas, or missing closing braces and brackets. The formatter highlights parsing errors and provides helpful hints.
Yes. Both .json and .txt files containing valid JSON are supported.
Yes. Nested objects and arrays are fully supported, and the formatter also calculates the maximum nesting depth.