How to use
- Paste your JSON into the input box (object, array, or a simple value).
- Pick an indent size: 2 spaces or 4 spaces.
- Click Format for readable indentation, Minify for a single line, or Validate to check syntax without changing the result area until you format or minify.
- Use Copy result to move the output into your editor, terminal, or test. Clear empties both input and output.
Everything runs in your browser. What you paste is not uploaded to any server and is never put in the page URL — useful when analytics or ads record visited addresses.
What it’s for
JSON shows up in REST APIs, config files, webhooks, test fixtures, and Postman or Insomnia payloads. When a response arrives as one long line — or a teammate sends a snippet with a trailing comma — spotting the mistake by eye is slow. A local formatter fixes that in seconds: paste, format, read the structure; if something is broken, the message points you at the problem without opening DevTools or writing a one-off script.
This page combines formatting, minifying, and validation. Indentation helps you review nested keys and compare diffs. Minifying shrinks the text for environment variables, test strings, or request bodies where size matters. Validate is the shortcut when you only need to know the text is legal JSON before it hits the backend.
Developers, QA, and anyone documenting APIs use this loop daily. In legacy code, “almost JSON” — single quotes, comments, trailing commas — fails JSON.parse. Better to catch that here than mid-deploy.
How it works
Browsers already ship JSON.parse and JSON.stringify. The tool uses those natives: on format or minify, the text is parsed; if syntax is fine, the value is serialized again with your chosen indent (or with no extra spaces when minifying). If parsing fails, the JavaScript engine’s error is shown in plain language — often with a character position — and the confused Kitto mascot sits beside the warning. When the JSON is valid, the happy mascot marks success.
There is no third-party library and no network upload. Closing the tab clears what was in memory. There is no cloud save, server-side history, or share link that embeds your payload — which avoids leaking tokens, personal data, or API secrets that sometimes sneak into test payloads.
Validation does not check a schema (required types, extra fields). It only answers: “is this syntactically valid JSON?” For OpenAPI or JSON Schema contracts, use your project’s tooling; here the focus is everyday work — reading, cleaning, and checking raw text.
Frequently asked questions
Is my JSON sent to a server?
No. Parsing, formatting, minifying, and copying all happen on your device. Nothing you paste is put in the URL or sent by this page.
What’s the difference between format and minify?
Format adds line breaks and spaces (2 or 4) for reading. Minify strips unnecessary whitespace into one line, useful for compact payloads.
Does it accept JSON with comments?
No. Standard JSON disallows comments and trailing commas after the last item. Remove those or convert to valid JSON before pasting.
Can I format very large files?
Yes, within what the browser can hold in memory. Huge files (tens of megabytes) may slow the tab; for those, prefer a command-line tool on your machine.
What does “position” mean in an error?
It’s the character index where the parser stopped — handy for missing quotes, extra commas, or unclosed braces. Count from the start of the pasted text.
Is an online formatter safe for sensitive data?
On this page, your content does not leave the browser. Still, avoid pasting real passwords or tokens on a shared machine; use test data when you can.