JSON Formatter / Validator

About JSON Formatter / Validator

The JSON Formatter, Validator, and Minifier gives you instant control over JSON data. Paste any JSON to pretty-print it with consistent indentation, validate its syntax and highlight errors with line numbers, or minify it by removing all unnecessary whitespace for production use.

JSON formatting is essential for reading API responses, debugging data structures, reviewing configuration files, and working with database exports. Minifying JSON reduces file size for transmission and storage.

The validator catches all JSON syntax errors: missing commas, trailing commas, unquoted keys, single-quoted strings, mismatched brackets, and invalid escape sequences — and shows the line and character position of each error.

Everything runs in your browser. Your data never leaves your device.

JSON Formatter / Validator Features

• Pretty-print or minify on demand

  Switch between a readable, indented layout and a fully minified single-line output for the same document, with adjustable indent width.

• Precise error locations

  Invalid JSON is flagged with the specific line and character position of the problem, instead of a generic parse-failure message.

• Collapsible tree view

  Browse large JSON documents in a collapsible tree alongside the raw text, so you can drill into nested objects and arrays without losing your place.

How to Use JSON Formatter / Validator

1. 1

   Paste your JSON into the input.

2. 2

   Click Format to pretty-print with indentation, or Minify to remove all whitespace.

3. 3

   Syntax errors are highlighted with the exact line and column number.

4. 4

   Copy the formatted or minified result.

Examples

{"name":"Alice","age":30,"city":"New York"}

{
  "name": "Alice",
  "age": 30,
  "city": "New York"
}

{
  "name": "Alice",
  "age": 30
}

{"name":"Alice","age":30}

{"user":{"id":1,"name":"Alice"},"active":true}

{
  "user": {
    "id": 1,
    "name": "Alice"
  },
  "active": true
}

{
  "event": "click",
  "target": "button"
}

{"event":"click","target":"button"}

Practical Uses for JSON Formatter / Validator

• Pretty-print a minified JSON API response for debugging
• Validate a JSON config file before deploying it
• Minify a JSON payload to reduce request size
• Spot a missing comma or trailing comma causing a parse error
• Sort object keys alphabetically for a consistent diff in version control
• Clean up JSON copied from a browser's network tab

Common Mistakes to Avoid

✕Leaving a trailing comma after the last item in an object or array.

✓Standard JSON doesn't allow trailing commas (unlike JavaScript object literals). Remove the comma after the final key-value pair or array element.

✕Using single quotes instead of double quotes for strings and keys.

✓JSON requires double quotes for all strings and object keys. Single-quoted values are valid JavaScript but not valid JSON.

✕Leaving comments in a file meant to be parsed as JSON.

✓JSON has no comment syntax. Remove // or /* */ comments, or switch to JSONC/YAML if you need comments in a config file.

Who Uses the JSON Formatter / Validator Tool

• Developers pretty-print API responses and catch JSON syntax errors while debugging.
• Backend engineers validate and minify JSON config files and payloads before deployment.
• QA engineers inspect and reformat JSON responses captured during API testing.
• Data analysts clean up and format JSON exports before further processing.
• Technical writers format JSON examples for clear, readable API documentation.

Comparisons

Frequently Asked Questions

What indentation size does it use?

2 spaces by default. Toggle to 4 spaces or tabs using the indentation selector.

What JSON errors does the validator catch?

Missing commas, trailing commas (not allowed in standard JSON), unquoted keys, single-quoted strings, mismatched brackets and braces, invalid escape sequences, and malformed numbers.

Does JSON allow comments?

Standard JSON (RFC 8259) does not allow comments. If your JSON has // or /* */ comments, you have JSONC (JSON with Comments), which is used in some config files like tsconfig.json.

What is the difference between JSON and JSONC?

JSONC allows // single-line and /* */ multi-line comments. Standard JSON parsers reject JSONC. Some tools (VSCode, tsconfig) support JSONC specifically.

Why minify JSON?

Minified JSON removes all whitespace, reducing file size for network transmission and storage. For a large JSON file, minification can reduce size by 20–50%.

Can I sort JSON keys alphabetically?

Yes — enable the Sort Keys option to alphabetically sort all keys in all objects throughout the JSON tree.

Can I fix a 'trailing comma' error automatically?

The validator identifies exactly where the trailing comma is with a line and column number; removing it and reformatting is a manual step, but the formatter's own output never includes trailing commas.

Can I use this to clean up JSON copied from a browser's network tab?

Yes — paste the raw response body and click Format to get properly indented, readable JSON, which is often much easier to review than the browser's default single-line display.

Does the formatter change the order of keys?

No, unless you enable Sort Keys. By default, keys keep their original order from the input; Sort Keys reorders them alphabetically at every level of the JSON tree.

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