JSON Formatter
Format and validate JSON with syntax highlighting
How to Use JSON Formatter
- 1
Paste your JSON into the input area.
- 2
Click Format to pretty-print the JSON with proper indentation.
- 3
Use Minify to compress it for production, or Validate to check for errors.
- 4
Copy the formatted or minified JSON from the output.
About JSON Formatter
Format, validate, and beautify JSON online. Pretty print with syntax highlighting. Minify JSON too. Free.
Best Use Cases
- •Prettifying a minified JSON API response so you can read and debug it
- •Validating JSON before using it in a config file or database
- •Minifying formatted JSON for use in production to reduce payload size
- •Checking JSON structure when an API call is failing unexpectedly
- •Cleaning up JSON copied from documentation or Stack Overflow
Examples
Minified to readable
Input: {"name":"Alice","age":30,"city":"Cape Town"} - Output is the same data with indentation, showing each key on its own line.
Syntax error detection
Input: {"name":"Alice","age":30,} - The validator flags the trailing comma as invalid JSON syntax and shows the line number.
Nested objects
A deeply nested API response with arrays of objects formats correctly into a readable tree structure with indented levels.
Common Mistakes to Avoid
- !Using single quotes around strings - JSON requires double quotes. 'name' is invalid; "name" is correct
- !Adding a trailing comma after the last item in an array or object - this is valid JavaScript but invalid JSON
- !Confusing JSON with JavaScript object literals - JSON is stricter and does not allow comments, functions, or undefined values
Limitations
- –The formatter does not sort keys alphabetically by default - key order is preserved from the input
- –Very large JSON files (over 5MB) may be slow to format in the browser
- –The tool formats JSON only. It does not convert JSON to other formats. Use the JSON to CSV or JSON to YAML tools for that.
Privacy
All JSON formatting happens locally in your browser. No data is sent to any server. Safe for API keys, configuration files, and internal data structures.
Frequently Asked Questions
How do I format JSON online?
Paste your JSON into the editor and click 'Format'. The tool will indent and colorize it instantly.
Can this validate JSON?
Yes. Any syntax errors are highlighted with the line number and error description.
What is minified JSON?
Minified JSON removes all whitespace to reduce file size - useful for API responses and production code.
What is the difference between Format and Minify?
Format (also called pretty-print) adds line breaks and indentation to make JSON readable by humans. Minify removes all whitespace to produce the most compact possible output for production use or API payloads.
Why does the formatter show a syntax error?
JSON has strict formatting rules. Common causes of errors include trailing commas after the last item in an array or object, single quotes instead of double quotes around strings, and missing commas between items.
Does JSON formatting change the data?
No. Formatting only changes the whitespace. The underlying data structure, values, and types are identical before and after formatting.
Can I format very large JSON files?
Yes, within browser memory limits. Files up to a few megabytes format instantly. Very large JSON files (tens of megabytes) may be slower on older devices.