JSON formatter & validator
Paste JSON to format it, minify it or find syntax errors. Everything happens in your browser, so API responses and config files stay private.
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🔒 Runs entirely in your browser – nothing you enter is uploaded or stored.
How to use it
- Paste your JSON into the left field.
- Click “Format” to pretty-print or “Minify” to compress it. Turn on “Sort keys” for a stable order.
- If the JSON is invalid, the message shows the line and column of the problem.
Last checked: October 2026. Found a mistake? Use the form below – we fix confirmed errors and update the date.
Frequently asked questions
Is my JSON sent to a server?
No. Parsing and formatting use your browser's built-in JSON engine. Nothing leaves your device.
Why is my JSON invalid?
Common causes are trailing commas, single quotes instead of double quotes, unquoted keys, comments, or missing brackets. The error position points to where the parser stopped.
What does “Sort keys” do?
It orders object keys alphabetically at every level, which makes two JSON files easier to compare – for example with our diff checker.
Is there a size limit?
Only your device's memory. Files of several megabytes format in a moment on a modern computer.