Format JSON without changing your data

Validate before formatting

Open the JSON Formatter & Validator, paste your JSON or open a text file, and choose the output you need. A syntax error reports where parsing stopped. JSON uses double-quoted property names and strings; comments and trailing commas are not valid JSON.

{"name":"Demo","enabled":true,"items":[1,2,3]}

Try removing the final closing brace to see the error feedback, then restore it. A syntax check confirms valid JSON grammar. It does not confirm that the data matches your application’s schema or business rules.

Watch numbers and duplicate keys

Identifiers can look like numbers but require exact preservation. Some programs convert JSON numbers to JavaScript numbers and lose precision for large integers. This formatter preserves numeric tokens rather than converting them through JavaScript numbers.

{"id":9007199254740993,"value":1.2300,"label":"first","label":"second"}

The formatter preserves the duplicate labels and the number spellings in this example. Other software may reject duplicate properties or keep only one of them. Fix ambiguous data deliberately before using it in another system.

Choose and check an output

1. Use readable formatting when reviewing structure with another person.
2. Use compact output when whitespace is unnecessary.
3. Check the tree for structure, but verify the exported text when exact tokens matter.
4. Copy or download the result, then test it in the program that will consume it.

The tool does not validate remote APIs or execute pasted code. Avoid private data if your workplace prohibits entering it in browser tools.

Questions & answers