JSON Fixer

JSON Fixer – Repair Broken JSON Online

Got a "Unexpected token" error and no idea where to start? The JSON fixer repairs invalid JSON automatically. Paste the broken text and get valid, nicely formatted JSON back — no manual hunting for the missing comma or the stray single quote.

What it fixes

• Quotes – adds missing quotes around keys, converts single quotes and typographic “smart quotes” to double quotes, and escapes quotes inside strings.
• Commas – removes trailing commas and inserts missing ones between items.
• Comments – strips // and /* */ comments.
• Python and JavaScript literals – True, False, None, undefined, and string concatenation.
• Truncated JSON – closes unclosed strings, arrays, and objects, which is handy for cut-off logs or streamed LLM output.
• Wrappers – JSONP callbacks, Markdown code fences, and MongoDB types such as ObjectId("...") or ISODate("...").
• Special whitespace and control characters that break strict parsers.

Typical situations

Developers often need to turn a JavaScript object literal, a Python dict printed to the console, or a snippet from a chat message into real JSON. Language models also regularly produce JSON with trailing commas or explanations wrapped around it. The fixer handles all of these in one click.

How it works

The tool uses jsonrepair, a well-tested open-source library, and then validates the result with the browser's strict JSON parser. Choose the indentation or minified output; the repaired JSON can be copied or downloaded.

Next steps

After repairing, check the structure in the JSON Viewer, remove empty fields with the JSON Cleaner, or verify the final file with the JSON Validator.