Tools · Text · JSON formatter and validator
JSON formatter and validator
Validate JSON as you type, pretty-print it or minify it, and see the exact line and column of any syntax error.
Runs fully in your browser. Nothing is uploaded.
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Try a different file, or try again.
How it works
Paste your JSON.
It's validated and formatted instantly - switch to Minify if you want it compact instead.
Copy the result, or fix the error at the exact line and column shown.
Frequently asked questions
No. Everything happens in your browser - not even to check if it's valid.
Yes - the exact line and column, not just "invalid JSON".
Yes. Switch to Minify mode and the same JSON comes back with no extra whitespace.
No. This tool validates strict JSON (RFC 8259) only. Comments, trailing commas and unquoted keys are reported as syntax errors, not silently accepted.
JSON.parse keeps the last value for a repeated key. The formatted output shows only the surviving one - that's standard JSON behavior, not a bug in this tool.
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