JSON Formatter
Paste messy API responses, config blobs, or minified payloads into this free online JSON formatter to pretty-print, validate, and minify JSON in your browser. Whether you need a quick JSON beautifier for debugging or a JSON validator that points to the exact line and column of a syntax error, everything runs locally - your data never leaves your browser.
Unlike upload-based tools, CodingFormatter uses a JSONC-aware parser so real-world pastes with comments or trailing commas can be cleaned into strict JSON. Choose indent size, optionally sort keys alphabetically, then copy, download, or share a compressed link. Ideal for backend developers inspecting REST responses and students learning correct JSON syntax.
Input
Paste or type your JSON here…
Output
Your formatted JSON will appear here
Frequently Asked Questions
Why does my JSON formatter show an error about a trailing comma?
Strict JSON does not allow trailing commas after the last property or array item. Many editors and JSONC accept them, but APIs often reject them. Remove the final comma or enable comment-tolerant parsing and re-format to a strict JSON output.
Is my JSON uploaded to a server?
No. CodingFormatter runs entirely in your browser with JavaScript. Your payload never leaves your device - ideal when pasting API responses that may contain tokens or PII.
Can I minify JSON as well as pretty-print it?
Yes. Use Format for readable indentation, or Minify to collapse whitespace into a single-line payload suitable for storage or network transfer.
What about duplicate keys?
JSON object key collisions are invalid in the spec but common in the wild. JavaScript keeps the last value for a duplicate key. Prefer unique keys; if you see surprising values, search for repeated property names in the input.
Does this tool support JSON5 or comments?
Yes for input - you can paste JSONC-style // and /* */ comments. On format, comments are stripped so the output is valid strict JSON.