JSON Formatter

Format, validate, and beautify JSON instantly in your browser.

FreeBrowser-basedInstant
Result
Paste or type JSON on the left to see it formatted here.

Your files are processed locally in your browser and are not uploaded to our servers. Formatting happens instantly as you type, using your browser's own JSON parser — nothing is sent anywhere.

How to use JSON Formatter

Paste or type JSON into the input box and this tool validates its syntax and reformats it with consistent indentation as you type. Invalid JSON is flagged with a clear line-and-column error message describing what to fix and where. Switch to Minify for a compact single-line output, then copy it to your clipboard or download it as a .json file.

Key features

  • Instant client-side formatting and validation as you type
  • Clear, line-and-column error messages for invalid JSON
  • Adjustable indentation (2 spaces, 4 spaces, or a tab)
  • One-click Minify mode for a compact single-line output
  • Syntax-highlighted result (keys, strings, numbers, booleans, null)
  • One-click copy to clipboard, or download as a .json file

Practical use cases

  • Debugging an API response before pasting it into documentation
  • Cleaning up minified JSON config files for readability
  • Validating hand-written JSON before committing it to a repository
  • Minifying a JSON config file before shipping it

Supported formats

Accepted: json

Limitations

  • Very large documents (tens of megabytes) may be slow on low-memory devices
  • Does not support JSON5 or JSONC comment syntax

Frequently asked questions

Does this tool store or upload my JSON?
No. All formatting and validation happens locally in your browser using JavaScript's built-in JSON parser. Your data is never transmitted or stored.
Is there a size limit?
There is no server-side limit, but very large JSON documents (tens of megabytes) may be slow to process depending on your device's available memory.
Can it also minify JSON, not just format it?
Yes. Switch the output mode from "Pretty" to "Minify" to get a compact, single-line version of the same valid JSON — useful for shrinking a config file before shipping it.

Part of Coding Tools