JSON Formatter & Validator
Paste messy or minified JSON to prettify it with clean 2-space indentation, validate it, or compress it back down for production — instantly, and without your data leaving the browser.
What this tool does
This is a JSON formatter, validator and minifier in one box. It parses your input with the browser's native
JSON.parse, so validation is exactly as strict as the parser your
application will actually use — not a loose approximation. If the document is valid you can re-indent it with two spaces
per level or strip every byte of insignificant whitespace.
Because the whole tool is client-side, it is safe for payloads you would not paste into an unfamiliar website: API keys, customer records, internal configs. The trade-off is that it is a formatter rather than a schema validator — it confirms your JSON is well-formed, not that it matches the shape your API expects. For very large documents (several megabytes) the browser's parser will be slower than a native desktop editor.
How to format JSON
- Paste your raw JSON into the editor. Minified API responses work as well as hand-written objects.
- Click Prettify (2 Spaces) to validate the document and re-indent it. If it parses, the formatted result replaces your input in place.
- Click Minify instead when you want the smallest possible payload for a request body or config file.
- If the JSON is invalid, an error banner names the exact problem. Fix the character it points at and run it again.
- Click Copy Result to put the output on your clipboard.
Common use cases
-
Reading an API response
A minified response from
curlor a network tab becomes a readable tree in one click. -
Debugging a parse error
Find the trailing comma or unquoted key that is breaking your app, with the exact position reported.
-
Shrinking a config file
Minify a JSON config or fixture before committing it, then prettify it again when you need to edit by hand.
-
Checking a webhook payload
Confirm a payload from a payment or CRM webhook is well-formed before you write parsing code against it.
Frequently asked questions
Is my JSON uploaded to a server?
No. Formatting, validation and minification all run in your browser using JavaScript's built-in JSON parser. Your data never leaves your device, which is why the tool is safe for API keys, customer records and internal payloads.
What is the difference between prettifying and minifying JSON?
Prettifying re-indents the JSON with two spaces per level so it is readable by a human. Minifying removes all insignificant whitespace so the payload is as small as possible for production. Both produce exactly the same data — only the formatting differs.
Why does my JSON fail to validate?
The most common causes are trailing commas before a closing brace or bracket, single quotes instead of double quotes, unquoted object keys, and JavaScript comments. JSON is stricter than JavaScript object literals — the error message shown above the editor names the exact character position of the problem.