Developer tools
JSON Formatter & Validator
Format, validate and minify JSON. Invalid syntax is reported with the exact position of the problem.
What is JSON Formatter & Validator?
JSON is the most common data interchange format between systems today, but the JSON that comes back from an API usually arrives as a single unbroken line that is effectively unreadable. Reformatting it with indentation and line breaks turns that wall of characters into visible structure.
Beyond formatting, this tool validates. When the syntax is wrong, the error message points to the exact character position — typically a trailing comma after the last element, a key missing its double quotes, or single quotes used where JSON requires double.
The reverse direction is here too. Minify strips every unnecessary space, producing the shortest valid form. That is useful for embedding JSON in an environment variable, pasting it into a command line, or cutting transfer size.
How to use
- Paste your JSON into the input area, or click Load sample to see it in action.
- Click Format to indent and expand it, or Minify to collapse it onto a single line.
- Pick 2 or 4 spaces of indentation to match your project's convention.
- If there is an error, read the red message — it tells you which character position is at fault.
- Click Copy to take the result.
Frequently asked questions
Is my JSON sent to a server?
No. Parsing and formatting use the browser's built-in JSON functions and run locally. That matters, because API responses routinely contain tokens, keys and personal data.
Why is my JSON rejected when it looks correct?
Three causes account for most cases: a trailing comma after the final element, keys not wrapped in double quotes, and single quotes instead of double. JSON is stricter than JavaScript object syntax, so something that runs fine in code is not necessarily valid JSON.
How large a file can this handle?
A few megabytes is routine. At tens of megabytes the browser may slow down, since the whole object tree has to be built in memory. For that scale, a command-line tool such as jq is a better fit.
Does it handle non-Latin text correctly?
Yes. Output preserves Unicode characters rather than escaping them to \uXXXX, so Vietnamese diacritics and Chinese characters appear exactly as you entered them.