JSON Formatter & Validator
Prettify, minify, and validate your JSON data instantly.
Professional JSON Formatting
Our JSON Formatter helps developers read and debug JSON data by adding proper indentation and validation. All processing is done client-side, ensuring your data never leaves your browser.
How to use the JSON formatter
- Paste JSON into the input box. The status label tells you immediately whether it is valid.
- Press Format to pretty-print it with 4-space indentation, or Minify to remove all whitespace for compact transfer.
- If the JSON is invalid, the output shows the parser's error message, which usually includes the position of the problem.
- Copy the result or press Clear to start again.
Parsing uses your browser's built-in JSON.parse, so API responses, configuration files and tokens you paste are never uploaded. That matters when the JSON contains customer data or credentials.
The most common JSON errors
| Error | Invalid | Valid |
|---|---|---|
| Trailing comma | {"a": 1,} | {"a": 1} |
| Single quotes | {'a': 'x'} | {"a": "x"} |
| Unquoted keys | {a: 1} | {"a": 1} |
| Comments | {"a": 1 // note} | Remove the comment. JSON has no comment syntax. |
| Special values | {"a": undefined}, NaN | Use null or a number/string. |
JSON basics
JSON (JavaScript Object Notation) is the standard text format for exchanging data between web services. It has six value types: objects ({} with string keys), arrays ([]), strings in double quotes, numbers, booleans (true/false) and null. It is defined in RFC 8259.
Formatting vs minifying
Formatted JSON is for humans: reviewing API responses, writing config files, or comparing changes in version control. Minified JSON is for machines: it is smaller to send and store. The data is identical either way.
Frequently asked questions
Why is a large number changed after formatting?
JavaScript represents numbers as 64-bit floats, so integers above 9,007,199,254,740,991 lose precision when parsed. If you work with very large IDs, keep them as strings in your JSON.
Does the formatter sort keys?
No. Keys stay in their original order.