Developers
JSON Formatter
Readable, valid, cleanly indented JSON — checked live as you type.
A payload squashed onto one line, a trailing comma that breaks the API call, a brace missing somewhere in a 500-line config: every developer has been there. Paste your JSON into this formatter and it is validated as you type, with every syntax error reported alongside its line number — no more hunting by eye. Then pick your indentation — two spaces, four spaces or tabs — for a readable document, or minify it instead to shave bytes before sending it over the network. Everything runs in your browser: your data never touches a server, so API responses and internal payloads are safe to paste. Free, no sign-up, no limits.
How does it work?
- Paste your JSON into the input area — it is validated instantly.
- Pick your indentation: 2 spaces, 4 spaces or tabs.
- Click “Format” to beautify it or “Minify” to compact it.
- Copy the result with one click.
Frequently asked questions
Why is my JSON invalid when it looks fine?
The usual suspects: a trailing comma after the last item of an object or array, single quotes instead of double quotes, unquoted keys, or comments — all habits carried over from JavaScript that strict JSON forbids. The error message here points to the offending line so you can fix it in seconds.
Can JSON contain comments?
No — the JSON standard has no comment syntax. If you need notes in a config file, use a dedicated field like “_comment”, or switch to a format that supports them (JSONC, used by VS Code, or YAML). JSON sent to an API must stay strictly standard.
When should I format and when should I minify?
Format when you need to read, debug, diff or commit the file: indentation makes the structure obvious. Minify for production payloads: it strips whitespace and line breaks. The saving is modest if your server already gzips responses, but it costs nothing.
Is my JSON uploaded anywhere?
No. Validation, formatting and minification all run inside your browser — nothing leaves your machine. You can safely paste internal data or API responses without any risk of leakage.