Format and validate JSON
Paste JSON or open a file. The page checks the syntax, shows errors with line and column, and formats or minifies the result.
Drag a JSON file hereChoose JSON file
One JSON file up to 50 MB. Best suited: a list of objects. Long numbers keep every digit.
Processed on your device, no upload
Enter or paste JSON to check it.
Advanced settings
Guide and details
How it works
- Paste JSON into the text field or open a file.
- The page checks the text at once. If there is an error you see the line, column and the spot in the text.
- Choose “Format” for readable or “Minify” for compact JSON. In the settings you set the indentation.
- Copy the result or download it.
Checking with understandable errors
The tool reads the JSON with its own parser following the JSON standard. It executes nothing and uses no eval. Typical errors such as a missing comma, a trailing comma, single instead of double quotes, comments or invalid values such as NaN are named. The error is shown with line, column and an excerpt, and a click jumps there in the input field.
For valid JSON you see short statistics, for example the number of objects and the nesting depth. Repeated keys within an object are reported.
Formatting and minifying
When formatting you choose two spaces, four spaces or tab. Optionally keys are sorted alphabetically or non-ASCII characters are written as \uXXXX. Numbers keep their digits exactly, even very long numbers are not rounded. The output is checked again with an independent parser.
The result is shown in the window up to a certain length; copying and the download always contain everything. Files up to 50 MB are processed in a background process so the page stays usable.
Frequently asked questions
Is my JSON uploaded?
No. Checking and formatting run in your browser.
Does formatting change my data?
No. Only spaces and line breaks change. The order of keys is kept unless you explicitly choose sorting.
Why is my JSON refused?
Because it does not follow the JSON standard. Trailing commas, single quotes or comments are common causes. The error message names the spot.
Are very long numbers changed?
No. The digits stay as they are and nothing is converted to floating point numbers.
Can I format very large files?
Up to 50 MB. Large files are not shown in the text field but are checked and formatted. You download the result.