JSON and Data
Processed locally in your browser — not uploaded
JSON Formatter
Format JSON with your choice of indentation, minify it to one line, or just validate it. Syntax errors are checked with a dedicated parser, not the browser's inconsistent built-in error messages, so you get an exact line and column every time. Runs entirely in your browser.
Output will appear here01
How to use
- Paste or type JSON into the input field.
- Choose Format to pretty-print with your chosen indentation, or Minify to compress it to one line.
- If the JSON is invalid, the exact line and column of the first problem is shown.
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Understanding the output
Formatting and minifying both first validate the JSON's syntax with a dedicated parser (not just the browser's built-in JSON.parse) so error locations are precise and consistent across browsers, rather than depending on each browser's own error message format.
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Common issues & tips
- •Trailing commas: JSON doesn't allow a comma before a closing } or ] — unlike JavaScript object/array literals.
- •Single quotes or unquoted keys: JSON requires double quotes around both string values and object keys.
- •Leading zeros in numbers (like 007) aren't valid JSON.
Frequently asked questions
- Why does the error message differ from my browser console?
- Each browser formats JSON.parse() errors differently, and some don't include a line/column at all. This tool uses its own JSON parser specifically to give a consistent, precise error location regardless of browser.
- Is my JSON sent to a server?
- No. Formatting, minifying and validation all happen locally in your browser.
- What's the difference between Format and Minify?
- Format pretty-prints with indentation for readability. Minify removes all unnecessary whitespace to produce the smallest valid output.