Paste JSON to validate it as you type, then format or minify it. Errors point to the exact line and column, and nothing you paste leaves your browser.
Format, validate and minify JSON online, and convert it to YAML, XML or CSV. Errors point to the exact line and column with a plain explanation, keys and values are colour-coded, and nothing you paste ever leaves your browser.
No. Everything runs in your browser. Nothing you paste or upload is sent anywhere, logged or stored, so it is safe to use with API responses and config files.
Most online formatters convert your text to JavaScript numbers and back, which silently rounds anything beyond 2^53 - an ID like 12345678901234567890 becomes 12345678901234567000. This tool keeps every number, escape and key exactly as written and only changes the spacing.
Every rule of standard JSON: trailing commas, single quotes, comments, unquoted keys, missing commas or colons, mismatched brackets, unclosed strings, leading zeros, NaN and Infinity, and Python-style True, False or None. Each error shows the line, the column and a plain explanation.
Yes. A key that appears twice in the same object is valid JSON but usually a mistake, because most parsers keep only the last value. The tool lists each duplicate with its line number as a warning.
There is no upload limit, because nothing is uploaded. Very large documents of several megabytes still work; above about 200 KB the colours are switched off to keep typing fast.