JSON Formatter & Validator
Format, validate, and minify JSON in your browser.
Paste messy or minified JSON and get it back clean and readable, or collapse pretty JSON down to a single line for transport. If the JSON is invalid, the formatter tells you what broke and roughly where, so you can fix it fast.
Everything runs in your browser. Your data is never uploaded, which matters when you're pasting API responses or config that shouldn't leave your machine.
How to use the JSON formatter
- Paste your JSON into the top box.
- Click Beautify to indent it, or Minify to strip whitespace.
- If there's an error, the status line points you to the problem.
- Use Copy to grab the result.
Beautify vs minify
Beautifying adds indentation and line breaks so a human can read the structure — ideal when you're debugging an API response or reviewing config. Minifying removes every optional space and newline to make the payload as small as possible, which is what you want in production requests and stored records. The data is identical either way; only the whitespace changes.
Common JSON errors
Most invalid JSON comes down to a handful of mistakes: a trailing comma after the last item, single quotes instead of double quotes, unquoted keys, or a stray comment (JSON doesn't allow comments). Numbers can't have leading zeros or a trailing decimal point either. When validation fails, check the position the status line reports and look just before it.
Reading a validation error
When JSON fails to parse, the browser reports where it gave up — often a line and column, or a character position. The real mistake is usually just before that point: a missing comma between two items, a value that was never closed with a matching brace or bracket, or a stray comma after the final element. Work backwards from the reported spot and check the nearest structural character. Once the structure is valid, beautifying it makes any remaining logical issues far easier to spot.
Why minified JSON exists
Every space and newline in a JSON payload is bytes on the wire. At the scale of an API serving millions of requests, stripping that whitespace measurably reduces bandwidth and speeds up transfers. That's why production responses arrive minified and hard to read. Beautifying restores the indentation locally so you can inspect it, without changing what the server sends. The data is byte-for-byte equivalent in meaning either way — only the presentation differs.
Frequently asked questions
Is my JSON uploaded to a server?
No. Formatting and validation happen entirely in your browser using the built-in JSON parser, so nothing you paste leaves your device.
Why does valid-looking JSON fail?
Usually a trailing comma, single quotes, unquoted keys, or a comment. Strict JSON requires double quotes and no comments or trailing commas.
What's the difference between beautify and minify?
Beautify adds indentation for readability; minify removes all optional whitespace to shrink the file. The underlying data is unchanged.
Does formatting change my data?
No. Beautifying and minifying only add or remove whitespace. Keys, values, order, and types are preserved exactly.
Can I format very large JSON files?
Yes, within your browser's memory. Because processing is local, there's no upload limit, but extremely large files depend on your device's available memory.
Last updated: 2026-01-15