JSON Formatter & Validator
Paste JSON below to pretty-print, validate, or minify it. Runs entirely in your browser — nothing is uploaded.
Last updated
How to format and validate JSON
- Paste your JSON.
- Click Format to pretty-print it with 2-space indents, or Minify to remove all whitespace.
- If the JSON is invalid, the error and its position are shown; otherwise click Copy result.
About this tool
This formatter parses your JSON with the browser's native JSON.parse, so validation errors match exactly what you'd get in your own code — including the character position of the problem. Formatting uses 2-space indentation; minify strips all whitespace to produce the smallest possible payload.
Numbers are kept exactly as you wrote them. A plain JSON.parse round trip would quietly turn a long ID like 12345678901234567890 into 12345678901234567000 (JavaScript numbers hold about 15–17 significant digits) and 1.0 into 1; this tool doesn't.
Nothing you paste here is sent to a server. The entire tool runs as JavaScript in your browser tab.
Questions about JSON
How do I find an error in my JSON?
Paste it and click Format. The error message says what’s wrong and where, using the same parser as JavaScript.
What are the most common JSON mistakes?
A comma after the last item, single quotes instead of double quotes, keys without quotes, and comments, none of which JSON allows.
Does it change long numbers?
No. Numbers stay exactly as written, so a long ID like 12345678901234567890 isn’t rounded, as it would be in plain JavaScript.
Is my JSON uploaded anywhere?
No. It’s formatted in your browser, so it’s safe to paste API responses and config files.