Format, minify, and validate JSON with syntax-error highlighting.
No. All formatting and validation happens in your browser via JavaScript's built-in JSON.parse and JSON.stringify. Sensitive JSON (API tokens, credentials) never leaves your machine.
Most common reasons: trailing comma after last item, single quotes instead of double, unquoted keys (valid JS but not JSON), unescaped special characters (quotes inside strings need \), BOM at start of file.
JSON5 allows comments, trailing commas, single quotes, and unquoted keys. This tool follows strict JSON (RFC 8259). Use JSON5-specific tools if you need those relaxations.
Yes, but browsers may slow down significantly above 5 MB. For very large files, consider command-line tools like jq. This calculator handles typical API responses (usually under 1 MB) instantly.