JSON Formatter & Validator
Paste JSON to pretty-print it, minify it or check that it is valid. Errors are shown with the line and column so you can fix them quickly. Everything runs in your browser, and your data is never uploaded.
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How to use it
- Paste your JSON into the input box, or press “Load sample” to try it.
- Choose the indentation (2 spaces, 4 spaces or tab) and, if you like, tick “Sort keys”.
- Press Format to pretty-print, Minify to remove all whitespace, or Validate to only check it.
- Copy the result or download it as a .json file.
Frequently asked questions
Is my JSON sent to a server?
No. The formatting and validation run in your browser using JavaScript. Nothing you paste leaves your device.
Why does my JSON show an error?
The most common causes are a trailing comma after the last item, single quotes instead of double quotes, keys without quotes, comments, and a missing comma between items. The error message shows the line and column.
What is the difference between format and minify?
Formatting adds line breaks and indentation so people can read it. Minifying removes all spaces and line breaks so the file is as small as possible, which is useful for network requests and storage.
Can JSON have comments?
No. Standard JSON does not allow comments. Some tools accept a relaxed format (JSON5 or JSONC), but strict parsers, including the one used here, reject it.
Why do very large numbers change after formatting?
JavaScript stores numbers as 64-bit floating point values, so integers above 9,007,199,254,740,991 lose precision. If you work with big IDs, keep them as strings.
Related tools
These tools run entirely in your browser and are provided free, without warranty. Check important results before using them in production.