JSON Formatter & Validator
Format or minify JSON and validate its syntax instantly, with errors pinpointed by exact line and column — free and entirely in your browser, nothing uploaded.
🔒 Your code never leaves the browser — not one character is sent anywhere, and nothing is stored
How to use it
- Paste or type your JSONThe tool checks from the first character — no button to press, nothing to wait for.
- Choose a formatting modeTwo spaces, four spaces, or minify for the smallest possible output.
- If there’s an error, see exactly whereLine and column appear below the box instead of a vague message that tells you nothing.
- Copy the resultThe copy button takes the formatted text, and clear empties both boxes at once.
Enjoying the tool? Help us keep it free forever — Support OMXHub ❤️
Frequently Asked Questions
How do you pinpoint the error location?
We read the line and column numbers from the error message your own browser returns — we don’t build a second JSON parser from scratch. Most modern browsers (Chrome, Firefox) report line and column; some older versions return only "invalid" with no detail. When that happens, we say so plainly rather than guess a wrong number.
Does key order change after formatting?
It can, and that’s JavaScript’s own behavior, not our bug: any key that looks like an integer ("1", "20") moves to the front of the object in ascending order, while string keys keep their original order. Try {"b":1,"2":2,"a":3} and watch "2" come out first.
What happens if I duplicate the same key twice?
Only the last value survives; the first one is silently dropped — that’s how JSON.parse behaves everywhere, not something we added. If your text contains duplicate keys, make sure that’s intended before relying on the output.
What’s the difference between formatting and minifying?
Formatting adds whitespace and newlines so the text becomes easy to read. Minify strips every unnecessary space to shrink the file — exactly the same data in fewer bytes. Format while reading or debugging; minify before shipping the file somewhere size matters.
Do you validate the data or just the syntax?
Just the syntax. We confirm your text is grammatically valid JSON — matched braces, commas where they belong, quoted keys. We don’t check whether the data makes sense for your application (say, whether "age" should be a number rather than a string) — that needs a schema specific to your project.
Is my text uploaded to a server?
No, not a single character. Formatting happens entirely inside your browser from the first keystroke.