JSON Formatter & Validator
Format, validate, and beautify your JSON data instantly.
About this tool
Paste any JSON payload — from a REST API response, a log line, or a config file — and this formatter will pretty-print it with two-space indentation, surface the exact line and column of the first syntax error, and let you minify it again for production use. Everything runs locally in your browser, so responses containing secrets, PII, or production data never leave your machine. Handy when you're debugging a webhook at 2 a.m., diffing two API versions, embedding compact JSON into a shell command, or just making a 4000-character single-line blob human-readable. Trailing commas, unquoted keys, and single-quoted strings are flagged the same way Node's strict parser sees them, so what validates here will validate in your app.
Features
- Format and beautify JSON with proper indentation
- Validate JSON syntax and pinpoint errors instantly
- Minify JSON for production use
- Copy formatted or minified output to clipboard
How to Use
- Paste your JSON data into the input field
- Click "Format" to beautify or "Minify" to compress
- Review validation status and any error messages
- Copy the result using the copy button
Frequently Asked Questions
Is my JSON sent to a server?
No. Formatting, validation, and minification all run in your browser via the native JSON parser. Nothing is uploaded, logged, or stored on our side, which makes it safe to paste payloads that include API keys, tokens, or customer data.
Why does my JSON say "Unexpected token" when it looks fine?
Strict JSON forbids trailing commas, single-quoted strings, unquoted object keys, and JavaScript-style comments. The error position we show is the first character the parser couldn't accept — usually the comma before a closing brace or a key written without double quotes.
Does minifying change the meaning of my JSON?
No. Minification only strips insignificant whitespace between tokens. Keys, values, numeric precision, and array order are preserved exactly, so the minified output is byte-for-byte equivalent to the formatted version once both are re-parsed.
Can I format huge JSON files?
The formatter handles multi-megabyte payloads fine on a modern laptop, but the browser UI can get sluggish past ~10 MB. For logs or database exports larger than that, prefer a streaming CLI tool like jq.
What's the difference between JSON and JSON5?
JSON5 is a superset that adds comments, trailing commas, unquoted keys, and single quotes — the ergonomics of a JS object literal. Most backend parsers don't accept it. Stick to strict JSON for anything leaving your browser, and use JSON5 only inside config files your own code controls.
Why does a floating-point number round-trip differently after I format it?
JSON's number type maps to JavaScript's IEEE-754 double, so 0.1 + 0.2 is still 0.30000000000000004. The formatter doesn't introduce drift — it just exposes precision you'd hit anywhere. For money or very large IDs, encode as a string.