JSON Formatter
Format, minify, and validate JSON with syntax highlighting and error detection. Free online tool, no upload needed.
Preparing private browser tool…
How to format and debug JSON
Use JSON Formatter when API responses, configuration files, or log payloads are hard to read. Formatting makes structure visible and helps find syntax errors quickly.
Steps
- Paste JSON into the editor.
- Format, minify, or validate the input.
- Copy the cleaned output or fix highlighted syntax errors.
Privacy note
The formatter runs in the browser. Pasted JSON is not uploaded, which matters for API payloads, internal logs, and test data.
Frequently asked questions
- Does it validate JSON syntax?
- Yes. Invalid JSON shows the exact parse error with line and column information.
- Can I minify JSON?
- Yes. Toggle between pretty-print (2/4/8 space indent) and minified (no whitespace) output.
- Does it support JSON5 or comments?
- No. Only strict RFC 8259 JSON. JSON5 features (comments, trailing commas, unquoted keys) are not supported.
- Is there a size limit?
- Practical limit is about 10MB - beyond that the browser UI slows down. For larger files, use a command-line tool.
- Does formatting change my data?
- The input is parsed and re-serialized, so key order is preserved but duplicate keys collapse to the last one, trailing zeros disappear (1.50 becomes 1.5), and integers beyond 2^53 lose precision.
- Is my JSON sent anywhere?
- No. Parsing and formatting use the browser JSON parser in the page, so payloads with tokens or customer data stay on your machine.