JSON Formatter
Pretty-print or minify JSON. Auto-detects, highlights syntax errors with line and column.
Quick answer: JSON Formatter: pretty-print or minify JSON. Auto-detects, highlights syntax errors with line and column. Runs entirely in your browser, free, no signup.
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This formatter leans on the browser's native JSON parser, which is both a strength and a boundary. The strength is speed and a strict, standards-accurate reading of your data. The boundary is that genuinely malformed JSON is rejected rather than guessed at — which is what you want, because silent auto-repair hides the very bugs you are trying to find.
When parsing fails, the error points at the line and column of the first problem, and the culprits are remarkably predictable. Trailing commas after the last item in an array or object, single quotes where JSON demands double, unquoted keys copied from a JavaScript object literal, and a missing closing bracket account for the overwhelming majority of failures. Jump to that coordinate and you will usually see it immediately.
Pretty-printing and minifying are two directions of the same operation: indent for humans reviewing a config or an API response, minify to strip every needless byte before storing or transmitting. Because it all runs in your browser, pasting a payload with real customer data or credentials never sends it anywhere — a meaningful difference from cloud-based formatters when you are debugging production data.
Frequently asked questions
- How do I format JSON?
- Paste your JSON into the input box and pick Pretty (2 or 4 spaces) or Minify. The result is shown immediately and can be copied with one click.
- How do I pretty print JSON?
- Click Pretty (2 spaces) or Pretty (4 spaces). The JSON is reformatted with consistent indentation, sorted nicely for human reading.
- Why is my JSON invalid?
- We point at the line and column of the first syntax error. The most common causes are trailing commas, single quotes instead of double, and missing closing brackets.
- How do I find a JSON syntax error?
- Paste the JSON and the error message will pinpoint the exact line and column of the problem, so you can jump straight to the fix.
- Can I format large JSON files?
- Yes — the limit is your device's memory. Files up to tens of MB format quickly on a modern laptop.
- Is my JSON data stored?
- No. Formatting runs entirely in your browser, so your data — even if it contains sensitive fields — never leaves your device.
- Can I minify JSON too?
- Yes. Click Minify to strip every space and newline, producing the smallest valid JSON for storage or transmission.
- What's the difference between JSON formatting and validation?
- Formatting changes how the JSON looks; validation checks whether it's syntactically correct. Both happen here at once — invalid JSON shows an error, valid JSON gets formatted.
- Can I format JSON on mobile?
- Yes. The tool works on phones and tablets.
- Is this JSON formatter free?
- Yes — free, no signup, no limits.