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Tools / JSON Formatter
FORMAT & VALIDATE

JSON Formatter

Turn dense JSON into readable structure. Catch duplicate keys and unsafe numbers before they disappear.

● PROCESSING STAYS ON YOUR DEVICE
PASTE OR OPEN A FILE
READ-ONLY
Ctrl / ⌘ + Enter

Example loaded. JavaScript processes it locally.

Review the output before using it.

Explore the JSON tree

Know what happens to your data.

Duplicate keys are rejected to avoid dropping values. Unsafe integers and numeric literals that would change decimal value are rejected. Ordinary numeric notation may normalize; this is not an arbitrary-precision calculator.

Practical limits

Inputs up to 1 MiB, 80 nested levels and 50,000 structured values. CSV supports up to 10,000 data rows and 200 columns. Very large jobs time out so your browser stays responsive. Uploaded files must be UTF-8 text.

Nothing is submitted to a processing server or saved as input history. Copy or download your result before leaving the page. Read the privacy details.