Free JSON Formatter
Format, minify and validate JSON locally with error locations, file import and downloads. Preserve numeric literals, including large integers, exactly.
Format your JSON
JSON result
No result yet.
How to use the JSON Formatter
- Paste JSON or import a UTF-8 file.
- Choose indentation, then Format, Minify or Validate. Errors report the line and column.
- Copy the result or download a JSON file. Reset clears input and output.
Practical example
Formatting {"id":9007199254740993,"active":true} adds whitespace without changing the large id value.
What inputs and outputs are supported?
| Input and limits | Pasted JSON or UTF-8 .json/.txt; up to 2 MB; maximum nesting depth 200 |
|---|---|
| Output | JSON with 2/4 spaces or tabs, or minified JSON; copy or .json download; formatting growth bounded to 10 MB |
Limits, assumptions and troubleshooting
A syntax parser checks JSON grammar and formats its original tokens. It never evaluates input and never converts numeric literals through JavaScript floating-point numbers. Key order, duplicate keys, escapes and numeric spelling are preserved. Duplicate keys are legal syntax here but downstream parsers may keep only one value. Comments, trailing commas, NaN, Infinity and JavaScript object notation are rejected.
Is my data private?
Input processing and output creation run on your device. This tool does not upload inputs, filenames or outputs, and analytics are disabled. The page loads normal website styles and fonts. Reset releases the current work; download a copy before leaving. This tool does not persist your input in browser storage.
Provided by Toolcross. Read our privacy policy or contact us with a reproducible issue. Updated .
Frequently asked questions
Can JSON be one line?
Yes. Minify removes formatting whitespace outside strings while preserving tokens. Whitespace inside strings is data and stays intact.
Does the JSON formatter store data?
No. Input and output stay in page memory. There is no upload, localStorage draft or analytics on this page.
Are large numbers rounded?
No. Numeric tokens are copied exactly, including integers beyond JavaScript’s safe integer range and exponent notation.
Can it repair invalid JSON?
It locates syntax errors; it does not guess repairs or strip meaningful data. Correct the input and validate again.