JSON Repair
Fix malformed JSON automatically. Repair trailing commas, single quotes, missing brackets, and more in one click.
JSON repair — fix malformed JSON automatically
A JSON repair tool automatically fixes common JSON syntax errors. FormatList's free online JSON repair tool handles trailing commas, single quotes, missing keys, unescaped characters, and missing brackets — all in your browser.
What errors can JSON repair fix?
- Trailing commas — removes extra commas after the last item in objects or arrays.
- Single quotes — converts single-quoted strings and keys to valid double-quoted JSON.
- Missing quotes on keys — wraps unquoted object keys in double quotes.
- Missing brackets — adds missing closing braces and brackets automatically.
- AI-generated JSON — fixes common issues in LLM and AI model output.
JSON repair FAQ
How does the JSON repair tool work?
It applies a series of automatic fixes: removing trailing commas, converting single quotes to double quotes, wrapping unquoted keys, and adding missing brackets. After each fix, it tries to parse the result and shows the repaired JSON or an error.
Can it fix AI-generated JSON?
Yes. AI models often produce JSON with trailing commas, single quotes, or missing brackets. This tool handles those common AI output issues automatically.
What JSON errors can it repair?
Trailing commas, single quotes instead of double quotes, unquoted object keys, missing closing brackets or braces, and basic unescaped character issues.
Is my data sent to a server?
No. All repair happens locally in your browser. Your JSON never leaves your computer.
What if the JSON can't be repaired?
If automatic repair fails, the tool shows the partially-fixed output along with a descriptive error message to help you fix the remaining issues manually.
Related JSON tools
Format, validate, repair, compare, escape, and transform JSON with these browser-based tools.