Validate, format and minify JSON instantly. Paste or upload your JSON, get precise error locations, prettify with indentation, and minify for production — all in your browser.
Opens the free browser-based tool — no sign-up needed
| Error | Wrong | Correct |
|---|---|---|
| Trailing comma | {"a":1, "b":2,} | {"a":1, "b":2} |
| Single quotes | {'key': 'value'} | {"key": "value"} |
| Unquoted key | {key: "value"} | {"key": "value"} |
| Missing comma | {"a":1 "b":2} | {"a":1, "b":2} |
| Undefined value | {"a": undefined} | {"a": null} |
| Comments | {"a":1 // comment} | {"a":1} |
Format / Prettify — adds indentation and line breaks so JSON is easy to read. Use when debugging an API response, reviewing a config file, or sharing JSON with a colleague.
Minify — removes all whitespace to produce the smallest possible string. Use when sending JSON in an API request, embedding in production code, or reducing payload size.
{} and []undefined, NaN or InfinityWhen an error is found, the validator shows the exact line number and column so you can jump straight to the problem.
Yes — completely. All validation uses JavaScript's built-in JSON.parse() running in your browser. Your JSON is never sent to any server. This makes it safe to paste API keys, database configs, authentication tokens and any other sensitive data.
{}) and ordered lists in arrays ([]).undefined instead of null..json file directly using the Upload File button. There is no size limit since everything runs in your browser — the only constraint is your device's available RAM.