JSON Formatter & Validator
Format, minify and validate JSON with exact error locations — without changing large numbers.
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How to use
- Paste JSON into the input box.
- Valid JSON is formatted instantly; problems are reported with a line, column and pointer.
- Choose pretty or minified output, the indent, and whether to sort keys.
- Copy or download the result.
How it works
A strict parser written for this tool gives the same clear messages in every browser — for example trailing commas, single quotes and comments, which are common in JavaScript but not allowed in JSON. Numbers keep their exact original digits, so IDs like 12345678901234567890 are never rounded (JSON.parse would change them). Duplicate keys produce a warning.
Limitations
- Very large files (tens of megabytes) may take a moment to format on low-end devices.
- JSON5 and JSON with comments are reported as errors, by design.
Privacy
Your text is processed entirely in this browser tab. Nothing is uploaded, logged or saved by this tool.
Local processing protects your data from being uploaded, but it cannot protect against a compromised device or malicious browser extensions.