JSON Formatter & Validator
Paste messy JSON and get clean, readable output in one click. Everything runs locally in your browser — your data never leaves your device.
Free Runs locally No signup
Input
Output
Formatted JSON will appear here.
Format with ⌘/Ctrl + Enter0 lines · 0 bytes
How to use it
1
Paste your JSON
Drop raw JSON into the input panel, or load the sample to see how it works.
2
Choose your formatting
Pick 2 or 4-space indentation, use tabs, or sort keys alphabetically.
3
Copy the result
The formatter validates as it parses. Copy or download the cleaned JSON.
Why use this tool
Runs entirely in your browser
No upload, no server, no logs. Sensitive payloads stay on your machine.
Real error positions
Invalid JSON reports the line and column so you can fix it fast.
Sort keys and minify
Normalize key order for stable diffs, or strip whitespace for production.
Frequently asked questions
Is my JSON uploaded anywhere?
No. Parsing and formatting happen in your browser using the native JSON engine. Nothing is sent to a server.
What is the maximum size?
There is no hard limit beyond your browser's memory. Files up to a few megabytes are usually instant.
Does it validate JSON?
Yes. Invalid input shows the line and column reported by the parser, and the output stays empty until the JSON is valid.
Can I format JSON with tabs?
Yes. Choose the Tab option in the indentation control to use tab characters instead of spaces.
Why did my key order change?
JSON objects are unordered. When Sort keys is enabled, keys are reordered alphabetically at every level to make diffs stable.
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