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Validate, pretty-print and minify JSON.
JSON Formatter validates, pretty-prints and minifies JSON. Paste any JSON to confirm it is well-formed, to make it readable with consistent indentation, or to compress it for transport.
Paste a JSON string into the input and run the tool. The probe parses, validates and reformats the JSON.
Input: JSON — e.g. {"ok":true}.
If the JSON is valid, the output is the pretty-printed (indented) version followed by the minified version. If it is invalid, the output reports the parse error and the position of the problem — a missing comma, an unquoted key, or a trailing comma are the most common causes.
→ Validate and pretty-print a JSON API response for debugging.
→ Minify a JSON config file to reduce its transfer size.
→ Find the exact position of a JSON syntax error.
→ Reformat minified JSON into a readable structure.
The most common causes are a trailing comma after the last item, unquoted object keys, single quotes instead of double quotes, or an extra/missing comma between elements. The error output points to the position of the problem so you can fix it.
Pretty-print adds indentation and newlines so a human can read the structure; minify removes all optional whitespace to produce the smallest possible string for transport. Both preserve the data exactly — only whitespace differs.
No. Standard JSON does not permit comments or trailing commas. Some parsers (JSON5, JSONC) accept them, but strict parsers will reject them. Remove comments before treating data as standard JSON.