JSON Validator
Check whether your JSON is valid and pinpoint what’s wrong. Paste or open a .json file: if it parses, you get a clean collapsible tree; if it doesn’t, you get the parser’s exact error so you can fix the stray comma or bracket — all in your browser.
- 🔒 100% private — no uploads
- 🆓 Free, no watermark
- 📱 Works on any device
How to validate
- 1
Paste or open your JSON
Type directly or paste your text into the box. It’s processed right in your browser — nothing is uploaded to a server.
- 2
See the result instantly
The tool updates live as you type, showing a valid tree or the exact error with no “submit” button or waiting.
- 3
Copy or keep going
Copy the result with one click, tweak your input, or clear it and start again. Free, instant and private.
Why use JSON Validator?
Pinpoints the error
Invalid JSON shows the JavaScript parser’s own message — the position and reason — so you can jump straight to the problem.
Tree view when valid
Valid JSON renders as a collapsible tree you can expand and collapse, making structure and nesting easy to check at a glance.
Open a file or paste
Validate a .json file straight from your device, or just paste text in.
100% private
Everything runs locally in your browser with JavaScript. Your text is never uploaded, stored or seen by anyone — it even works offline.
Validate JSON without uploading it
JSON you need to validate is often a config file or an API response carrying tokens and personal data. This validator parses everything in your browser with the same engine your code uses, so it catches exactly what your app would — and your data never leaves the device.
Common JSON mistakes the validator catches
Trailing commas after the last property, unquoted keys, single quotes instead of double, and unescaped newlines inside strings are the top culprits. The error message gives the exact line/character so you can fix it without a second guess. Once it’s valid the tree view makes the structure obvious at a glance.
Frequently asked questions
How does it decide if JSON is valid?
It parses the input with the browser’s native JSON parser — the same one your JavaScript uses. If parsing succeeds the JSON is valid; if not, you see the parser’s error message and position.
Is my text uploaded to a server?
No. The tool runs entirely in your browser, so whatever you type or paste stays on your device. It’s safe for code, tokens and confidential text, and works offline once loaded.