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SleekPrompt

JSON Formatter & Validator

Format, beautify, minify and validate JSON instantly. Errors show the exact line and column. Runs 100% in your browser.

JSON input

empty

Formatted JSON

Ready

How to use the JSON Formatter

  1. 1

    Paste your JSON into the left panel, or drop a .json file onto it.

  2. 2

    The formatted result appears on the right as you type — no button to press.

  3. 3

    Use Beautify, Minify or Sort keys, then copy or download the result.

Frequently asked questions

Why does my JSON fail to validate?

The most common causes are trailing commas, single quotes instead of double quotes, unquoted keys, and comments. This tool reports the exact line and column of the first error so you can jump straight to it.

What is the maximum file size?

There is no imposed limit. Because parsing happens on your own machine, the practical ceiling is your available memory — files of several hundred megabytes are typically fine on a modern laptop.

Is my data uploaded to a server?

No. Every tool on this site runs entirely inside your browser using JavaScript. Your input never leaves your device and is never sent over the network, which means it is safe to paste production data, API responses and tokens.