JSON syntax checker

Validate JSON syntax, format with proper indentation, and get detailed error messages instantly.

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14,352+

Total Calculations Run

< 15ms

Browser Execution Speed

100%

Client-Side Privacy

4.9 / 5.0

User Satisfaction

Worked Example & Common Values

Below is a sample worked calculation demonstrating how JSON syntax checker processes input data instantly inside your browser.

Sample Input Minified string: {"id":1,"status":"active","roles":["admin"]}

Computed Result

{
  "id": 1,
  "status": "active",
  "roles": [
    "admin"
  ]
}

Execution Mode Client-Side In-Browser JS

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About This Tool

This JSON Syntax Checker is a comprehensive tool for validating, formatting, and analyzing JSON data. Simply paste your JSON code or upload a JSON file, and the tool will instantly check for syntax errors, validate structure, and provide detailed error messages with line numbers. You can also format messy JSON with proper indentation (2 or 4 spaces), minify JSON by removing whitespace, and view statistics like character count and nesting depth. The tool highlights syntax errors directly in the editor and provides clear explanations to help you fix issues quickly. No data is sent to servers - all processing happens locally in your browser for privacy and speed.

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How to Use

Paste your JSON code into the textarea or click 'Upload JSON File' to select a file from your computer.
Choose validation options: enable strict mode to reject duplicate keys or trailing commas.
Click 'Validate JSON' to check for syntax errors and get detailed results.
Use 'Format JSON' to beautify with proper indentation or 'Minify JSON' to remove whitespace.
View results in the output panel showing formatted JSON, error details, and statistics.
Copy the validated/formatted JSON to clipboard with one click.

Frequently Asked Questions

Find Quick Answers

Does this tool send my JSON data to a server?

No, all JSON processing happens entirely in your browser using JavaScript. Your data never leaves your computer, ensuring complete privacy.

What JSON standards does this validator support?

The tool validates against the official JSON specification (RFC 8259). It checks for proper syntax, valid data types (strings, numbers, objects, arrays, booleans, null), correct quoting, and proper structure.

Can I validate large JSON files?

Yes, the tool can handle large JSON files, but very large files (over 10MB) may cause browser performance issues. For best results, we recommend files under 5MB.

What's the difference between 'Validate' and 'Format'?

'Validate' checks your JSON for syntax errors and reports any issues. 'Format' rearranges valid JSON with proper indentation and line breaks to make it more readable, but doesn't fix syntax errors.

Does the tool support JSON with comments?

No, standard JSON doesn't support comments. If you enable strict validation mode, comments will be flagged as syntax errors. You can disable strict mode to ignore comments during validation.

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