{ } JSON Formatter & Validator

Paste JSON, get it validated and pretty-printed with syntax highlighting — everything stays in your browser. Free, no account needed.

Input
Output

About this tool

Paste messy or minified JSON and get it validated, pretty-printed and syntax-highlighted instantly. The JSON Formatter points at the exact position of a syntax error, so a stray trailing comma or missing quote is found in seconds instead of minutes.

It also minifies: turn a readable document back into the smallest valid form for config files, API payloads or embedding in code. Everything runs client-side — API responses containing tokens or personal data never leave your machine.

How to use it

  1. Paste your JSON into the input box.
  2. Click "Format" to validate and pretty-print, or "Minify" to compress.
  3. If it is invalid, read the error message — it names the line and character.
  4. Copy the result with one click.

Frequently asked questions

Is my JSON uploaded anywhere?

No. Parsing, formatting and highlighting run entirely in your browser using the native JSON parser.

Why does it reject JSON with comments or trailing commas?

Standard JSON (RFC 8259) allows neither. The tool validates against the standard so you catch exactly what a strict parser in production would reject.

What is the size limit?

There is no hard limit; multi-megabyte documents format fine, limited only by your browser's memory.

Also on this page

JSON Validator · JSON Minifier

Free, private, no account. Like every DevForge tool, this one runs in your browser and never uploads your files. See all 35 free tools or join the DevForge community to share your own games, tools and assets.

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