Paste raw or minified JSON below to instantly format, validate, and beautify it with proper indentation. This tool catches syntax errors and highlights the exact location of problems — essential for debugging API responses, config files, and data exports.
Last updated: June 2026
Paste messy or minified JSON and get perfectly formatted output with your choice of indentation. The validator shows exactly where syntax errors occur. Minify mode strips all whitespace for compact JSON.
Minified JSON is efficient for data transfer but nearly impossible for humans to read. Formatted (or "pretty-printed") JSON adds indentation and line breaks that reveal the structure of the data, making it easy to inspect, debug, and edit. Every developer working with APIs, configuration files, or data processing needs a reliable JSON formatter.
Debugging API responses — paste the raw JSON response from your browser's developer tools or API client like Postman to see the data structure clearly. Editing configuration files — many tools and frameworks use JSON for settings (package.json, tsconfig.json, .eslintrc). Validating data — quickly check whether a JSON string is syntactically correct before submitting it to an API or database.
Valid JSON must follow these rules: data is organized in key-value pairs; keys must be strings enclosed in double quotes; values can be strings, numbers, booleans (true/false), null, arrays, or nested objects; no trailing commas are allowed; no single quotes (only double quotes); no comments are allowed in standard JSON.
Format mode adds whitespace and indentation for readability. Choose 2-space, 4-space, or tab indentation depending on your project's convention. Minify mode does the opposite — it strips all unnecessary whitespace to produce the smallest possible string, ideal for network transmission and storage.
| Error | Cause | Fix |
|---|---|---|
| Trailing comma | {"a":1, "b":2,} — comma after last item | Remove the comma after the final value or element |
| Single quotes | {'name': 'value'} — JSON requires double quotes | Replace all single quotes with double quotes |
| Unquoted keys | {name: "value"} — keys must be strings | Wrap all keys in double quotes: {"name": "value"} |
| Missing brackets | Unclosed [ or { somewhere in the data | Count opening and closing brackets; add the missing one |
| Comments in JSON | // comment or /* block */ in the data | Remove all comments — JSON does not support them |
The tool will tell you exactly where the syntax error is located, but it cannot automatically fix invalid JSON. Common issues include missing quotes around keys, trailing commas, and mismatched brackets.
There is no enforced limit, but very large JSON documents (over 10 MB) may cause your browser to slow down. For enormous datasets, a desktop tool or command-line utility may be more appropriate.
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