JSON Validator
Validate JSON syntax and format. Check for errors, show line numbers, and pretty-print valid JSON — all in your browser, no upload.
About the JSON Validator
This JSON validator runs entirely in your browser. Paste any JSON into the box above and click Validate to check its syntax. If the JSON is valid, you'll see a success message and a pretty-printed version. If there's an error, the tool shows the error message along with the line and column where the problem occurred.
Features
- Validate — Parses your JSON and reports whether it is valid, with line and column numbers on errors.
- Format — Pretty-prints valid JSON with 2-space indentation for readability.
- Minify — Removes all unnecessary whitespace to produce the smallest valid JSON.
- Clear — Resets the input and result so you can start over.
How to use the validator
- Paste your JSON into the input box.
- Click Validate to check syntax, or Format / Minify to reformat valid JSON.
- Read the result panel — valid JSON shows a formatted preview; invalid JSON shows the error and its location.
Frequently asked questions
Does this tool upload my JSON? No. All parsing happens locally in your browser. Your data never leaves your device.
How are line numbers calculated? The tool reads the error position reported by the browser's JSON parser and converts it into a line and column by counting newlines in your input.
Can it handle large JSON files? Yes, up to the limits of your browser's available memory. Very large files may take a moment to format.
Does it support JSON with comments? No. Standard JSON does not allow comments. Comments will be reported as syntax errors.