JSON Formatter Online Free — Beautify, Minify & Validate
The free JSON Formatter takes messy or minified JSON and instantly formats it with proper indentation, making it readable. It also validates syntax and reports errors — paste invalid JSON and the error location is shown immediately. All processing is in your browser.
How to Format JSON
- Open the JSON Formatter.
- Paste your JSON into the input field.
- Select 2-space or 4-space indentation.
- Click Format to pretty-print the output.
- Use Minify to remove all whitespace and produce the most compact form.
- Click Copy to copy the result to your clipboard.
If the JSON has a syntax error, the formatter highlights the problem and shows the line and character position of the error.
Pretty-Print vs Minify: When to Use Each
| Mode | Output | Use Case |
|---|---|---|
| Pretty-print (2-space) | Indented, readable | Debugging, reading API responses, documentation |
| Pretty-print (4-space) | Indented, more spacious | Code files, config files, team style preferences |
| Minify | No whitespace, single line | Production API payloads, embedded config, reducing bandwidth |
Common JSON Syntax Errors
Trailing commas
Standard JSON does not allow a comma after the last item in an object or array. This is valid JavaScript but invalid JSON:
{"name": "Alice", "age": 30,}Remove the trailing comma after 30. The formatter will identify the exact position of the error.
Unquoted keys
JSON requires all object keys to be quoted strings. This is valid JavaScript but invalid JSON:
{name: "Alice"}Correct form: {"name": "Alice"}
Single quotes
JSON strings must use double quotes. Single-quoted strings are invalid:
{'name': 'Alice'}Correct form: {"name": "Alice"}
Comments
JSON does not support comments. If you need annotated configuration, consider JSONC (JSON with Comments) or YAML, but strip comments before parsing as standard JSON.
Working with API Responses
Most HTTP APIs return JSON in minified form — all on one line with no whitespace. Paste the raw API response into the formatter and click Format to make it readable. You can then inspect the structure, find the field you need, and identify any unexpected values.
If you need to convert the JSON to another format for further processing, the CSV to JSON Converter and JSON to XML Converter handle common transformation needs.
Validating Configuration Files
Many tools use JSON for configuration — package.json, tsconfig.json, .eslintrc.json, and similar files. Paste any config file into the formatter to check for syntax errors before committing or deploying. The validator catches issues that would otherwise produce cryptic runtime errors.
Format and Validate JSON Free Online
Pretty-print, minify, and validate syntax instantly. No signup, browser-based.
Open JSON Formatter