Fix Single Quotes and Trailing Commas
Input
{
name: 'Ada',
scores: [100, 95,],
}Example output
{
"name": "Ada",
"scores": [
100,
95
]
}JSON Repair & Syntax Fixer Online
JSON & Data100% Client-SideReady
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About this tool, examples & FAQ
Automatically detect and repair syntax flaws in malformed JSON. Fixes single quotes, unquoted keys, trailing commas, JavaScript/C-style comments, Python literals (True, False, None), and unclosed brackets with an explicit change log.
Key facts
| Common Fixes | Single quotes, unquoted keys, trailing commas, comments, and missing brackets |
|---|---|
| Python Dict Support | Converts True, False, and None to true, false, and null |
| Maximum Input | 5 MB |
| Execution Deadline | 3 s |
How to use
- Paste broken, malformed JSON or a Python dictionary into the input area.
- Click Repair JSON (or press Ctrl/Cmd + Enter).
- Review the list of automatically repaired syntax modifications.
- Copy, download, or Send To another developer utility.
Example
Edge cases
Unclosed brackets and braces
When copying truncated API responses or logs, trailing brackets like '}' or ']' are often clipped off. The repair engine tracks the bracket stack and appends necessary closing delimiters.
Python dictionary syntax
Python outputs print dictionaries with single quotes ('key': 'val') and capitalized booleans (True, False, None). These are automatically converted into RFC 8259-compliant JSON.
Comments in JSON
JSON does not formally support comments. Line comments (//) and block comments (/* */) are stripped out during repair while preserving string contents.
How it works
- Scans and tokenizes the input text stream, preserving string literals.
- Identifies single quotes, unquoted object keys, JavaScript comments, and language constants.
- Normalizes tokens, eliminates trailing commas, and balances unclosed brackets.
- Validates and formats the resulting JSON document purely inside a local Web Worker.
Related workflows
JSON Validator
Validate JSON syntax, inspect structure, and diagnose syntax errors with line and column diagnostics.
JSON Formatter
Prettify, indent, and format JSON strings with customizable indentation and key sorting.
JSON Key Sorter
Sort JSON object keys alphabetically in ascending or descending order, with optional case sensitivity, recursive sorting, and array element sorting.
Frequently asked questions
Why do so many APIs and logs output invalid JSON?
Developers frequently copy objects directly from Python logs (which use single quotes and True/False/None), JavaScript console outputs (which omit quotes on keys), or truncated error logs.
Can I see what was changed during repair?
Yes. The output status and metadata report the exact modifications performed, such as converted quotes, stripped comments, or removed trailing commas.
Is my broken data sent to a cloud server?
No. All repair logic runs entirely within your browser's Web Worker. Your data is never uploaded, tracked, or saved remotely.
References
- RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format — JSON syntax specification for quotes, keys, arrays, and values