JSON Formatter & Validator
JSON Formatter & Validator: Paste JSON to format (pretty-print with your chosen indent), minify, or validate it. If the JSON is invalid you get the exact parser error, including the position of the problem, so you can fix it fast. All parsing happens locally in your browser.
Data as of 2026-06-13.
How it works
The formatter parses your input with the browser's native JSON.parse. If parsing succeeds the value is re-serialized with JSON.stringify — pretty-printed with your chosen indent, or minified to a single line with no whitespace.
If the JSON is invalid, the native parser error is shown along with the approximate line and column of the failure, computed from the character position in the error message. Validate-only mode reports validity without producing output.
Runs fully client-side in your browser. Source: published web standards (RFCs and the WHATWG/W3C specifications), as implemented by your browser. Verified 2026-06-13.
Frequently asked questions
What does the validator check?
It checks that the text is syntactically valid JSON per the JSON.parse rules: balanced brackets, quoted keys and strings, valid numbers, and no trailing commas. It does not validate against a schema.
Why does it reject trailing commas or comments?
Standard JSON does not allow trailing commas or comments. Formats that do (JSON5, JSONC) are supersets; paste strict JSON, or remove those features first.
Can I minify JSON to save bytes?
Yes. Choose the Minify action to strip all insignificant whitespace and produce the most compact valid representation of your data.
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Last updated: 2026-06-13