This JSON repair tool automatically fixes the most common JSON syntax errors — trailing commas, JavaScript-style comments, single-quoted strings, and unquoted keys. All repair logic runs entirely in your browser using native JavaScript. Your JSON never leaves your device. Paste broken JSON on the left and get corrected, formatted output on the right instantly.
The JSON repair tool fixes: trailing commas before } or ] (the most common error), JavaScript-style line comments (// ...) and block comments (/* ... */), single-quoted strings replaced with double quotes, and unquoted object keys (e.g. {key: "value"} → {"key": "value"}). After applying all fixes, it attempts JSON.parse and shows what was changed.
No. The repair tool only removes or corrects syntax issues — it never changes the actual values or structure of your data. Trailing commas, comments, and quote style are syntax artifacts; removing them does not alter what the JSON represents.
Trailing commas are allowed in JavaScript objects and arrays, but JSON (RFC 8259) explicitly forbids them. They appear when JSON is written by hand or generated by code that mimics JS syntax. For example: {"name": "Alice",} is valid JavaScript but invalid JSON. The repair tool removes these automatically.
Yes. JSON does not support comments (they were intentionally excluded from the spec), but developers often add // or /* */ comments when writing configuration files. The repair tool strips both line comments and block comments before attempting to parse.
No. All repair logic runs entirely in your browser using native JavaScript. Your JSON never leaves your device. You can verify this by opening DevTools → Network tab and watching for zero outbound requests while the tool runs.