JSON Formatter
Format, validate and minify JSON with clear error messages.
About JSON Formatter
JSON Formatter turns compact JSON into an indented layout that is easier to read, or removes formatting whitespace with Minify. It also checks whether the pasted text can be parsed as JSON and shows a parser error when it cannot. Use it while debugging API responses, reviewing configuration files or comparing the structure of a small data sample.
Formatting does not validate your application’s schema or prove that values are correct. It checks JSON syntax, then serializes the parsed value. Paste JSON text rather than a JavaScript object literal: property names and string values need double quotes, and comments and trailing commas are not valid JSON. The output updates immediately, with options to copy it or download a JSON file.
How to use JSON Formatter
- Paste the JSON
Enter text in JSON input. Parser errors appear when the syntax is invalid.
- Choose a layout
Select Format for two-space indentation or Minify for compact output.
- Review the result
Read the formatted structure or fix the input if an error is shown. Processing is automatic.
- Copy or download
Use Copy or the JSON download action once valid output is available.
Example: Readable API data
The compact input contains an object with a name and an enabled flag. Format displays the same parsed structure with indentation.
Input
{"name":"Ada","enabled":true}Output
{
"name": "Ada",
"enabled": true
}How it works
The tool calls the browser’s JSON.parse on the input. If parsing succeeds, JSON.stringify creates the output: Format supplies an indentation size of two spaces, while Minify supplies no indentation. Parsing happens before formatting, so an invalid document cannot simply be made valid by choosing Format. An error message comes from the browser parser and may describe the location or type of syntax problem.
This is a parse-and-serialize process, not a text-preserving editor. Whitespace and some numeric spellings change, duplicate object keys collapse to the value retained by the parser, and key order can follow JavaScript’s object-property ordering. Numbers also use JavaScript numeric precision; very large integer identifiers are safer represented as strings when the data format allows it. A syntactically valid document can still be unsuitable for an API if required fields or types are wrong.
When is this useful?
- Read a minified API response.
- Locate syntax issues in a configuration sample.
- Prepare compact JSON for a test fixture.
Things to know
- This checks syntax, not JSON Schema or application rules.
- Comments, trailing commas and single-quoted strings are not accepted.
- Duplicate keys and numbers beyond JavaScript precision may not survive unchanged; keep an original copy.
Privacy & processing
Formatting and parsing use the browser’s native JSON functions. Pasted JSON is held in tool state and is not uploaded to a ToolMyth server for formatting.
Frequently asked questions
Why is a JavaScript object literal rejected?
JSON has stricter syntax. Keys and strings need double quotes, and comments, undefined values and trailing commas are not valid JSON.
Does valid JSON mean my API request is correct?
No. The parser checks syntax, not required fields, data types defined by a schema or server-side business rules.
What does Minify remove?
It serializes the parsed value without formatting whitespace. Spaces inside string values remain part of those strings.
Will very large integer values stay exact?
Not necessarily. JavaScript numbers have limited integer precision. Preserve large numeric identifiers as strings when appropriate and compare the output with the original.