JSON formatter & validator
Make JSON easier to read, or compact it for transport, while keeping the original beside the result.
Ready when you are.
A practical example
Input or settings
{"name":"Café","active":true,"items":[1,2]}Example result
{
"name": "Café",
"active": true,
"items": [
1,
2
]
}When this helps
Useful for inspecting API responses, reviewing configuration snippets or preparing compact JSON. Choose two spaces, four spaces or tabs for readable output.
How it works and its limits
Both modes validate standard JSON syntax first. Comments, trailing commas, single-quoted strings and JavaScript expressions are rejected. Top-level strings, numbers, booleans and null are valid JSON too.
Formatting changes whitespace outside strings only. Number spellings such as 1e400 and integers beyond JavaScript’s safe range are preserved exactly, as are key order, escaped strings and duplicate key entries. Duplicate keys may still cause interoperability problems in another parser.
Validation checks syntax, not a JSON Schema or an API contract. The input limit is 200,000 characters, nesting is limited to 200 levels and output to 1,000,000 characters. Errors clear the previous result.
Useful details
Will large IDs be rounded?
No. The formatter retains original number tokens instead of serializing parsed JavaScript numbers.
Does valid JSON mean my API will accept it?
No. Required fields, types and business rules need separate validation.
Are duplicate keys removed?
No. Entries remain as written; another parser may keep only the last value.