JSON Fixer / Repair
Automatically fix malformed or broken JSON data. Repair missing quotes, trailing commas, single quotes, and other common JSON syntax errors.
Last updated: March 2026
Why use a JSON Fixer?
JSON is the most popular data interchange format, but it is extremely strict about syntax. A single missing quote or a trailing comma can cause entire applications to crash or APIs to reject requests.
Developers often encounter malformed JSON when:
- Copying data from logs or console outputs.
- Working with non-standard JSON exporters.
- Manually editing configuration files.
- Dealing with truncated API responses.
Key Features of our JSON Repair Tool
- Automatic Quote Correction: Converts single quotes to double quotes and adds missing quotes to object keys.
- Comment Removal: Strips out JavaScript-style comments (// and /* */) which are illegal in standard JSON.
- Trailing Comma Cleanup: Removes pesky trailing commas that break strict JSON parsers.
- Structural Heuristics: Attempts to identify the start and end of JSON structures within larger text blocks.
- Syntax Highlighting: The output is beautifully formatted and ready for use.
Standard JSON vs. JavaScript Objects
Many developers confuse JavaScript objects with JSON. While they look similar, JSON requires double quotes for all keys and string values, and does not allow comments or trailing commas. This tool bridges that gap by converting "JSON-like" JavaScript objects into valid, RFC-compliant JSON.
Frequently Asked Questions
What kind of JSON errors can this tool fix?
The JSON Fixer can repair common syntax errors such as missing quotes around keys, single quotes instead of double quotes, trailing commas in arrays or objects, JavaScript-style comments, and missing values. It can also strip leading/trailing non-JSON characters like variable assignments.
Is my data safe when using the JSON Fixer?
Yes, 100% safe. Like all tools on devtoolspack, the JSON repair process happens entirely in your browser. Your data is never sent to our servers or any third party.
Can it fix all JSON errors?
While it handles most common syntax issues, it cannot fix structural logical errors where data is fundamentally missing or corrupted beyond recognition (e.g., a completely truncated file or random binary data).
Does it support large JSON files?
Yes, it can handle large JSON payloads. However, performance may vary depending on your browser's memory and the complexity of the errors.
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