Key Statistics
Real-time syntax error detection Validation
Prettify or minify with one click Formatting
Color-coded JSON structure Syntax highlighting
Format & Validate JSON — Free Online Tool
Paste your JSON below to instantly format, validate, or minify it. Get syntax-highlighted output with proper indentation. If your JSON has errors, the tool shows exactly where the problem is with line numbers. All processing happens in your browser—your data stays private. No limits, no signup, completely free.Input
Output
All JSON processing happens locally in your browser. No data is sent to any server.
What is JSON Formatter?
JSON Formatter is a free tool that formats, validates, and beautifies JSON data. It transforms messy, single-line JSON into readable, indented format with syntax highlighting. It also validates JSON structure and shows detailed error messages with line numbers when something is wrong. The minify option compresses JSON for production use.
Essential for developers working with APIs, configuration files, data analysis, or debugging JSON responses.
How does JSON Formatter work?
- 01 Paste your JSON data into the input area
- 02 Click "Format" to prettify with proper indentation and syntax highlighting
- 03 Click "Minify" to compress JSON into a single line for production
- 04 If JSON is invalid, see the exact error location with line and column numbers
- 05 Click "Copy" to copy the formatted output to clipboard
- 06 Use "Clear" to reset and start with new JSON data
Why use a browser-based tool?
- Complete privacy: JSON data never leaves your device
- Works offline: Once loaded, works without internet
- Instant processing: No server round-trips, results appear immediately
- No data limits: Process large JSON files without restrictions
- Secure for sensitive data: API keys, config files stay on your machine
Common Questions
Why is my JSON invalid?
Common JSON errors: missing commas between items, trailing commas after last item (not allowed), using single quotes instead of double quotes, unquoted property names, missing closing brackets. This tool shows the exact line and position of the error to help you fix it quickly.
What is the difference between format and minify?
Format (prettify) adds indentation and line breaks for human readability—great for debugging and editing. Minify removes all whitespace to reduce file size—ideal for production, APIs, and storage. A 100KB formatted file might become 60KB when minified.
Can I format JSON with comments?
Standard JSON does not support comments—this is a common source of validation errors. If your JSON-like file has comments (// or /* */), you're likely working with JSON5 or a configuration format like tsconfig.json. Remove comments before validating as standard JSON.
How do I fix "Unexpected token" errors?
"Unexpected token" usually means invalid syntax. Common fixes: ensure strings use double quotes (not single), check for missing commas between array/object items, verify all brackets and braces match, remove trailing commas. The error message shows the exact position—look at that line in your original JSON.
Can I validate JSON from an API response?
Yes. Copy the raw JSON response from your browser's DevTools Network tab and paste it here. The tool validates the structure, shows any errors, and formats it for easy reading. Great for debugging API integrations and understanding response structures.