JSONFix.tech — JSON Repair Tools

Repair Malformed JSON Automatically

Stop manually fixing JSON. Paste malformed JSON, click one button, get perfect JSON back with an explanation of every change.

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What Makes JSON "Malformed"?

JSON (JavaScript Object Notation) is strict. Unlike JavaScript itself, JSON does not permit: trailing commas, single-quoted strings, unquoted keys, comments, or non-standard literal values like undefined. A single violation causes JSON.parse() to throw a SyntaxError.

Malformed JSON typically comes from: AI model output, hand-edited config files, JavaScript object literals pasted into JSON context, API responses from poorly implemented servers, or truncated streams.

All Error Types JSONFix.tech Repairs

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Trailing commas
Removes commas before } and ] that break strict parsers.
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Unquoted keys
Adds double quotes around unquoted object keys.
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Single-quoted strings
Converts 'single' quotes to "double" quotes.
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JavaScript comments
Strips // line comments and /* block comments */.
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Markdown code fences
Removes ```json and ``` wrappers from LLM output.
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Truncated JSON
Closes unclosed braces and brackets from cut-off responses.
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JS values
Replaces undefined, NaN, Infinity with JSON-legal null.
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Missing commas
Inserts missing separators between properties.

The jsonrepair Engine + AI Layer

JSONFix.tech is built on top of the battle-tested jsonrepair library (2.5M npm downloads/week), extended with a custom pre-processing layer that handles LLM-specific issues before the core repair runs.

After repair, Claude Haiku analyses what changed and generates a plain-English explanation — so you understand the root cause, not just the fix.

Repair Any Malformed JSON — Free

No sign-up. Works with JSON from any source.

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