Tool
JSON Formatter
Format and validate JSON while preserving large integers.
Try it
This tool runs entirely in your browser. Nothing you type or paste is sent anywhere.
Paste JSON to format it with consistent indentation. The tool validates the structure before it reformats, so malformed input is reported instead of silently changed.
Usage
- Paste or type a JSON document.
- Choose an indentation size.
- Review the validation result before copying the output.
Example
{"name":"example","enabled":true}Supporting content
Formatting is only useful when you can trust the parser that produced it. This tool shows the original number literals, so an identifier such as 9007199254740993 never changes value, and it reports the first syntax problem instead of guessing.
Limitations
Frequently asked questions
- Is my input sent to a server?
- No. The tool is designed to run in the page; nothing is uploaded by this static page.
Sources
- RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format — IETF (accessed 2026-09-01)