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developer
Free online JSON formatter and validator. Pretty-print, minify and check JSON syntax with clear error messages. Runs in your browser, nothing is uploaded.
Enter your values and select Calculate to see the result.
JSON is the standard format for exchanging data between web apps, APIs and configuration files, but minified or hand-edited JSON is hard to read and easy to break with a missing comma or quote.
Paste your JSON and choose pretty-printed with spaces or tabs, or minified. The tool validates the syntax and reports the position of the first error. Everything runs in your browser, so private payloads and tokens are never uploaded.
JSON.parse(input), then JSON.stringify with the chosen indentation
Paste JSON to validate it and get a formatted or minified version. Nothing leaves your browser.
It checks that your JSON is valid and then pretty-prints it with 2-space or tab indentation, or minifies it into a single line.
No. Parsing and formatting happen entirely in your browser, so private data stays on your device.
Common causes are trailing commas, single quotes instead of double quotes, unquoted keys and comments. The message shows the position of the first problem.
No. Only whitespace changes. Key order and values stay the same, although duplicate keys keep only the last value.