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JSON Repair

Repair broken JSON in your browser: trailing commas, unquoted keys, single quotes, and missing commas are fixed and re-validated. Nothing is uploaded.

Paste broken JSON and click Repair. Trailing commas, unquoted keys, single quotes, and stray values are fixed and re-validated.

Broken JSON
Repaired output
What this JSON repair tool does
Fix broken or malformed JSON in your browser. Trailing commas, unquoted keys, single quotes, missing commas, unterminated strings and stray values are repaired automatically and returned as valid JSON. Nothing is uploaded.
How it works
1. Check. Your input is parsed with a strict, RFC 8259-compliant parser. Already-valid JSON is formatted as-is.
2. Repair. If parsing fails, a tolerant parser fixes the common mistakes: it adds missing quotes around keys and strings, replaces single quotes, drops trailing commas, inserts missing commas, and turns stray values like undefined or NaN into valid JSON.
3. Re-validate. The repaired text is parsed again with the strict parser, so the result is guaranteed valid JSON.
4. Done locally. Your data never leaves the page.
Frequently asked questions
What JSON errors can it fix?
Trailing commas, unquoted keys, single quotes, missing commas, unterminated strings, and stray values such as undefined or NaN.
Is the repaired JSON guaranteed valid?
Yes. The repaired output is re-validated with a strict RFC 8259 parser, so the result is always valid JSON.
Does it upload my data?
No. Repair happens entirely in your browser — nothing is uploaded.
Does JSON Repair upload my data?
No. JSON Repair runs entirely in your browser — your input never leaves this page.
Is JSON Repair free to use?
Yes. JSON Repair is completely free, with no account and nothing to sign up for.
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Updated 2026-08-07 · Runs in your browser — your data never leaves this page.