JSON Formatter, Beautifier & Validator
Format, validate, and beautify JSON data instantly. Paste minified JSON and get readable, indented output in one click — free and 100% client-side.
🔒 100% Client-Side Processing
Your data is processed entirely in your browser and never transmitted to any server.
0 / 100M Limit
Common Use Cases
Debugging API responses
Paste a minified response from curl, Postman, or browser DevTools and instantly see its structure — nested objects, missing fields, and the exact location of any syntax error.
Validating config files
Check package.json, tsconfig, or any JSON config for trailing commas and unquoted keys before they break a build.
Preparing readable documentation
Format example payloads with consistent indentation before pasting them into API docs, READMEs, or bug reports.
Frequently Asked Questions
- What is JSON pretty print?
- Pretty printing outputs JSON with human-readable indentation and line breaks instead of a single compressed line. This tool pretty prints with 2-space indentation — paste minified JSON and click Format to get a readable, nested structure.
- Does this JSON formatter validate my JSON?
- Yes. Input is run through the browser's native JSON.parse(), so invalid JSON — missing commas, unquoted keys, trailing commas, mismatched brackets — is caught immediately with the exact error location, making the tool a real-time JSON linter.
- Can I format JSON from an API response with sensitive data?
- Yes. Parsing happens locally in your browser, so API keys, tokens, and PII in the payload are never transmitted anywhere. For shrinking a payload instead of expanding it, use the companion JSON Minifier.
- Why does my JSON show as invalid even though it looks fine?
- The most common causes are a trailing comma after the last item, single quotes instead of double quotes around keys and strings, unquoted keys, and JavaScript-only values like undefined or NaN — all valid in a JS object literal but rejected by strict JSON. This tool surfaces the parser's exact error message and position so you can find the offending character instead of scanning the whole payload by eye.
- Is there a size limit on how much JSON I can format?
- The input accepts up to 100 million characters — enough for the largest API responses, database dumps, or log exports. Formatting is debounced by 500ms so the UI stays responsive while you paste or edit large payloads.
- What is the difference between JSON and a JavaScript object literal?
- JSON is a strict text-based data format: keys and string values must use double quotes, trailing commas are forbidden, and only strings, numbers, booleans, null, arrays and objects are allowed — no functions, undefined, comments, or dates. A JavaScript object literal is more permissive (single quotes, unquoted keys, trailing commas, live functions). Code that copies a JS object literal into a JSON field usually needs these differences fixed first, which is exactly what this formatter's validation catches.
- Is there a Chrome extension for this JSON formatter?
- No — and you don't need one. This page works the same in any browser with no install, no extension permissions to grant, and nothing running in the background between visits. Bookmark the page instead of installing an extension and you get the same instant access without a third party able to read every page you browse.
- Is a JSON formatter the same as a JSON beautifier or prettifier?
- Yes — "formatter", "beautifier", and "prettifier" are used interchangeably for the same job: taking compact or inconsistently-indented JSON and re-outputting it with readable line breaks and indentation. This tool does that job under all three names.
- How do I format JSON in Python or JavaScript?
- Python: json.dumps(data, indent=2) after loading it with json.loads(). JavaScript: JSON.stringify(obj, null, 2). Both produce 2-space indented output — paste the result here to double-check it before shipping it in code.
- Is my data private when I use this tool?
- Yes. This tool runs entirely in your browser using client-side JavaScript — nothing you type is transmitted to, logged by, or stored on any server. You can safely process confidential text, tokens, or code.