A QUICK WALKTHROUGH
How to use this tool
- Paste JSON or choose a UTF-8 JSON file.
- Select two spaces, four spaces or minified output.
- Format and validate; correct any reported line and column error before exporting.
How it works
The parser builds a syntax tree while retaining raw number and string tokens. Formatting changes structural whitespace without converting number tokens into JavaScript floating-point values. Duplicate object keys are rejected because consumers disagree about which value survives. This is syntax validation, not a check against an application schema.
A practical example
Start with
{"id":9007199254740993,"active":true}What to expect
The integer 9007199254740993 remains exactly the same after formatting.
Important considerations
JSON does not allow comments, trailing commas or single-quoted strings. The tool does not guess repairs. Nesting is limited to 50 levels and input to 5 MiB.
5 MiB per input · 50,000 records · 200 columns. Input remains in page memory until you reset or leave. Copy and download actions are initiated by you. No tool input is sent to a processing service.
One more useful detail
Does valid JSON mean my API will accept it?
No. The API can require particular keys, types and values beyond JSON syntax.