JSON Formatter & Validator

What this JSON formatter does

Paste JSON into the input box and choose one of four actions. Format reindents it so each key and value is easy to read. Minify removes the spaces and line breaks to make it as compact as possible. Validate checks whether the text is correct JSON. Clear empties both boxes. Everything runs in your browser, so the data is never sent to our servers, which matters when the JSON holds private records or configuration.

How to use it

1. Paste your JSON into Input JSON.
2. Press Format / Beautify to see it indented with two spaces per level. The result appears under Output.
3. Press Minify to produce a single-line version with no extra whitespace.
4. Press Validate to confirm the JSON is correct. A valid input shows a confirmation message, and an invalid one shows the error in a red box.
5. Press Copy to copy the output to your clipboard.

Worked example

Pasting {"name":"John","age":30} and pressing Format produces:

{
  "name": "John",
  "age": 30
}

Minifying that output returns the original single line. If you add a comma after 30, the text becomes invalid, because JSON does not allow a trailing comma. Validate then shows a SyntaxError in the red box. The exact wording of that message depends on your browser.

What counts as valid JSON

JSON is stricter than JavaScript. Keys and strings must use double quotes. Comments are not allowed, and neither are trailing commas, single quotes or unquoted keys. Very large integers can lose precision when parsed, and if the same key appears twice, the last value wins.

Tips and limits

• Validate first when you are unsure. The error message points to the place where parsing failed, which is easier to fix before you reformat.
• Format always uses two spaces. There is no option to change the indentation.
• Minify reduces the size of JSON before you send or store it, but keep an unminified copy for editing.
• Very large files can slow the page down, because all the work happens on your own device.