JSON Formatter & Validator
Format, validate, and minify JSON with syntax highlighting. Spot errors instantly with detailed messages and line-by-line validation.
Runs in your browser. No data leaves your device.
Frequently Asked Questions
How does the JSON Formatter work?
The tool parses your input with JSON.parse(), which validates the syntax and converts it into a JavaScript object. It then re-serializes it with JSON.stringify(obj, null, indent) using your chosen indentation level. Syntax errors are caught by the parser and reported with the exact position and nature of the problem. Minification uses an indent of 0 to strip all whitespace.
How do I format JSON online?
Paste your JSON into the input area and it will be formatted automatically with proper indentation. You can choose between 2-space, 4-space, or tab indentation styles.
Why is my JSON invalid?
Common issues include trailing commas after the last item in an array or object, single quotes instead of double quotes around keys and strings, unquoted keys, or missing commas between items. The validator shows the exact line and position of the error.