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Developer tools·Data Formats

JSON Formatter

Format, minify, sort keys, and validate JSON with readable errors. Fully client-side — no account, uploads, or remote storage.

Added Apr 18, 2026 · Updated Apr 29, 2026

Input

Result

Enter a value for action to see your result.

How it works

Formats, minifies, and validates JSON. Pretty-print with configurable indentation, minify for compact storage, or validate structure and report the exact line and column of any syntax error.

Step by step

  1. 01Paste your JSON into the input field.
  2. 02Choose Format to pretty-print, Minify to compact, or Validate to check syntax.
  3. 03For formatting, select 2 spaces, 4 spaces, or tab indentation.
  4. 04Errors show the line and column number of the problem.

Examples

Format JSON

Adds newlines and 2-space indentation.

Inputs

Action:
format
Indent:
2
JSON Input:
{"name":"Alice","age":30}

Result

Output:
{ "name": "Alice", "age": 30 }
Status:
Valid JSON

Minify JSON

Removes all whitespace.

Inputs

Action:
minify
Indent:
2
JSON Input:
{ "name": "Alice", "age": 30 }

Result

Output:
{"name":"Alice","age":30}
Status:
Valid JSON

More about this tool

All formatting, minifying, and validation happens entirely in your browser using the native JSON.parse() and JSON.stringify() APIs. Nothing is sent to a server.

Format vs Minify

Formatting adds indentation and newlines to make JSON human-readable. Choose 2 spaces (most common), 4 spaces, or a tab character.

Minifying removes all whitespace to reduce byte size — useful for API responses, localStorage values, and network payloads.

Error Reporting

When JSON is invalid, the formatter reports the exact line and column of the error by counting newlines up to the character offset returned by the JavaScript engine. Common errors:

  • Trailing comma after the last item in an object or array
  • Single quotes instead of double quotes around strings or keys
  • Unquoted object keys
  • undefined, NaN, or Infinity values (not valid JSON)

Input Limit

Input is capped at 1 MB to keep the browser responsive. For larger files, use a local tool like jq.

Related guides

  • What Is JSON?

    Learn what JSON (JavaScript Object Notation) is, how to read and write it, common syntax errors, and best practices for using JSON in APIs and configuration.

  • Common JSON Syntax Mistakes (and Quick Fixes)

    Common JSON Syntax Mistakes (and Quick Fixes) -- JSON looks simple until the comma bites you. Free reference with links to matching on-site calculators.

  • JSON vs XML — When to Use Each Format

    A direct comparison of JSON and XML covering syntax, verbosity, data types, namespaces, and schema validation — with clear guidance on when to use each format.

Frequently asked questions

How do I fix a JSON syntax error?

The formatter reports the exact line and column where the error was found. Common mistakes: missing quotes around keys, trailing commas, using single quotes instead of double quotes.

What is the difference between formatting and minifying?

Formatting adds indentation and newlines to make JSON human-readable. Minifying removes all unnecessary whitespace to reduce file size, which is useful for API responses and storage.