JSON formatter and validator
Paste JSON below to format, minify or check it. Everything happens in your browser. The text is never uploaded, and this page has no analytics.
Need more than this? The PureJSON browser extension shows JSON files and API responses as a collapsible tree with copy-path, and keeps big numbers exact. Install it from
Edge Add-ons or
Firefox Add-ons (Chrome coming). I build it; this page is a free companion and works without it.
Common JSON errors
- Trailing comma after the last item:
{"a":1,}is not valid JSON. - Single quotes instead of double quotes:
{'a':1}is not valid JSON. - Unquoted keys:
{a:1}is JavaScript, not JSON. - Comments (
//or/* */) are not allowed. - Missing comma between items, or a missing closing bracket.
Note: this page uses your browser's own JSON parser. Numbers larger than 253 can lose precision when reformatted, because JavaScript stores them as floating point. If exact big numbers matter, use a tool that keeps them as text (PureJSON does).