Skip to main content
Toolzum

JSON Formatter

Prettifies JSON and API response data with configurable indentation, sorting, and syntax validation — fixes malformed JSON and makes nested structures readable.

100% Local Browser Native

How to Use the JSON Formatter

1. Paste JSON

Paste JSON text into the input area. Nothing runs until you trigger it.

2. Format

Format with indent and style options.

3. Copy output

Copy the clean output for your project.

Similar Tools You Might Need

See all

Frequently Asked Questions

What does the formatter do to my JSON?

It pretty-prints minified JSON with proper indentation, sorts keys alphabetically (optional), and collapses or expands nested brackets. Malformed JSON gets flagged with the exact line number of the syntax error.

Can I choose the indent size?

Yes. Select from 2 spaces (default), 4 spaces, tabs, or minified output. The indent setting applies instantly as you switch between options.

Does it validate JSON syntax?

Yes. If your JSON has syntax errors — missing commas, trailing braces, unquoted keys — the tool highlights the exact location and describes the error so you can fix it quickly.

Can I sort JSON keys?

Yes. Toggle key sorting to arrange all object keys alphabetically. This is useful for comparing two JSON structures or making large configs easier to navigate.

Is my JSON data uploaded?

No. All formatting and validation happens locally in your browser using the JSONLint library. Your data never leaves your device.

What happens if I drop a .json file on the homepage first?

The dropped file auto-fills the input as long as it is 1024 x 1024 bytes (1 MB) or smaller; larger files are ignored. Formatting itself offers 3 buttons: Format (2 spaces), Format (4 spaces) and Minify.

Last updated October 2026