JSON Fixer — Repair Broken JSON Online
Automatically detect and fix common JSON syntax errors. Repairs trailing commas, single quotes, unquoted keys, undefined values, and JavaScript comments. Free, 100% client-side — your data never leaves your browser.
Broken JSON Input
Fixed JSON Output
What JSON Errors Does the Fixer Repair?
The JSON Fixer automatically corrects the most common JSON syntax errors that prevent JSON from parsing correctly. These errors frequently occur when copying JSON from JavaScript code, API documentation, or log files.
| Error Type | Broken Input | Fixed Output |
|---|---|---|
| Trailing commas | {"name": "Alice", "age": 30,} | {"name": "Alice", "age": 30} |
| Single quotes | {'name': 'Bob'} | {"name": "Bob"} |
| Unquoted keys | {name: "Charlie", age: 25} | {"name": "Charlie", "age": 25} |
| Undefined value | {"result": undefined} | {"result": null} |
| JS comments | { // user data "name": "Dave" } | { "name": "Dave" } |
When to Use the JSON Fixer
The JSON Fixer is most useful when you're working with:
- Copied JavaScript objects — JavaScript object literals use single quotes and unquoted keys, which are not valid JSON. The fixer converts them automatically.
- API responses with comments — Some tools add JavaScript comments to JSON responses for documentation. The fixer strips these out.
- Hand-written JSON — Common mistakes like trailing commas after the last item are automatically removed.
- Config files — JSON config files are often edited manually and accumulate trailing commas or single-quote usage over time.
Limitations of Auto-Fix
The auto-fix feature cannot repair all JSON errors. It works best for surface-level syntax mistakes. For deeply malformed JSON with missing brackets, mismatched nesting, or severe structural problems, you will need to manually inspect the error message and correct the JSON. Use the JSON Formatter & Validator to get precise error line numbers for manual debugging.