04 / Forge / Developer / Client-side
JSON formatter and validator
Format, minify, and validate JSON with the exact line and column of any error. Runs entirely in your browser; nothing you enter leaves the page.
What this JSON formatter does
Paste any JSON and choose Format to indent it for reading or Minify to strip whitespace for transport. Validate parses the text with the browser's own JSON parser, so the verdict matches what JavaScript would accept.
When the input is invalid, the tool reports the line and column where parsing stopped and the parser's message. That is usually a trailing comma, a single-quoted string, an unquoted key, or a missing bracket.
When to use it
Reading an API response that arrived on one line. Checking a configuration file before a deploy. Shrinking a payload to see its real size. Finding the one character that breaks a JSON file a colleague sent.
Privacy
This tool runs entirely in your browser. The text is never sent to a server, so it is safe for payloads that contain tokens, customer records, or anything else you would not paste into a random website.
Questions
Is this JSON validator free?
Yes. There is no account, no limit, and no upload. The page is a static file and the work happens in your browser.
Why does it say my JSON is invalid when it looks fine?
The most common causes are a trailing comma after the last item, single quotes instead of double quotes, comments, or an unquoted key. JSON is stricter than JavaScript object syntax.
Does formatting change my data?
No. Formatting and minifying only change whitespace. Key order and values are preserved exactly.
What is the size limit?
Whatever your browser can hold in a text field. Multi-megabyte files work; very large ones may take a moment to parse.
Have a project in mind?