FileSwift
Home/JSON Formatter
Free · runs in your browser · secure offline formatting

Format & Validate
your JSON, privately.

Validate, prettify, and minify raw JSON data. Everything runs locally in your browser—making it fully safe to format keys, configs, and production payloads without uploading a single byte to external servers.

Input size
0 KB
Output size
0 KB
Size saved
🛡️ Private Local Parsing: Your data never leaves your device and is never uploaded or saved. Disconnect your internet to test—this page works 100% offline.

JSON Formatter & Validator

Paste your raw JSON text below to prettify, validate, or minify it instantly in your browser.

Input Raw JSON
Formatted Output

Common questions

Is my data sent to any server?

No. FileSwift runs entirely client-side. The JSON parser is executed locally by your browser's V8 engine. None of the text you paste leaves your device or goes through any server.

What happens if my JSON is invalid?

The formatter will instantly locate the syntax error. A red error panel will display the exact reason and position of the error (such as missing commas, bad quotes, or unclosed brackets) so you can fix it.

Does this tool support large files?

Yes. Because the formatting runs directly inside your computer's RAM rather than waiting for a slow network upload queue, it can handle large JSON logs and config files in milliseconds.

Understanding JSON Formatting & Minification

JSON (JavaScript Object Notation) has become the standard data interchange format for modern web applications and APIs. While computers can parse JSON regardless of whitespace or line breaks, humans need structured formatting to read and debug it. A standard JSON block contains key-value pairs, nested arrays, and objects enclosed in braces and brackets.

Prettifying JSON inserts clean indentation (commonly 2 or 4 spaces) and newlines. This makes it easy to read configuration files, audit data structures, and identify syntax issues. Minifying JSON, on the other hand, removes all unnecessary whitespace, comments, and line breaks to compress the text size, reducing bandwidth usage when sending payloads across networks.

FileSwift combines formatting, minification, and strict syntax validation inside one offline workbench. If your JSON contains a trailing comma, missing quotes, or mismatched braces, our validator highlights the exact line of the syntax error so you can fix it immediately. Since we run entirely in client-side RAM, your code is 100% private.