JSON Formatter & Validator

How this works & your privacy

🔒 Nothing you paste, type, or drop is uploaded, stored, or logged. All processing happens in your browser and the data never leaves your device — close the tab and it is gone.

Your input is parsed with the browser's native JSON parser and re-serialised with your chosen indentation (2, 4, tab, or minified); optional key-sorting produces canonical output. Invalid JSON is reported with the line and column plus a plain-English explanation of the likely cause. Beyond parsing, a lightweight tokenizer scans the raw text for duplicate keys and integers outside JavaScript's safe range — signals that JSON.parse erases — and computes statistics (objects, arrays, properties, depth, value types) for the tree view.

Limitations

• Formatting normalises whitespace and (optionally) key order; it never changes values, so numbers keep their exact JSON representation.
• The interactive tree view is limited for very large documents (tens of thousands of values) to stay responsive; formatting and validation still work at any size.
• Comments and trailing commas are not valid JSON and are reported as errors — this is a strict RFC 8259 parser, not JSON5.

Standards & references

• RFC 8259 — The JSON Data Interchange Format ↗
• ECMA-404 — The JSON Data Interchange Syntax ↗