JSON Formatter & Validator
Free JSON formatter and validator. Catch syntax errors with line info.
100% runs in your browser — no upload, no trackingHow to use
Paste JSON and click Validate & Format. Syntax errors are reported with position.
Example
{ "a": 1, "b": [2,3] }
FAQ
Is my data uploaded to a server?
No. Every tool runs entirely in your browser. Your input never leaves your device.
Is this tool free?
Yes, all DevToolbox tools are free to use with no account required.
Does it work on mobile?
Yes, the interface is mobile-friendly and responsive.
How accurate is the conversion?
We use standard, well-tested algorithms (Web Crypto, Intl, DOMParser). Results match common reference tools.