Fix broken, malformed, or invalid JSON automatically.
Paste malformed JSON, JavaScript object literals, or Python dictionaries. Our fault-tolerant repair engine normalizes quotes, removes trailing commas, strips comments, and restores spec-compliant JSON in one click.
{
"name": "JSONGlow Repair Engine",
"version": 2,
"active": true,
"description": "Fixes trailing commas, missing quotes, Python literals & comments!",
"tags": [
"parser",
"ast",
"repair"
],
"stats": {
"memory_mb": 256,
"null_value": null,
"debug": false
},
"timeout_ms": 5000,
"author": "Developer"
}JSONGlow's JSON Repair tool is a free, browser-based utility that automatically fixes malformed JSON, trailing commas, single quotes, and Python dictionaries without sending data to a server.
Overview
How the fault-tolerant JSON repair engine restores broken payloads
JSON is notoriously rigid: a single misplaced comma, an unquoted object key, a stray single quote, or a Python boolean literal (`True` instead of `true`) will cause standard parsers like JavaScript's `JSON.parse()` or Python's `json.loads()` to crash with immediate syntax errors.
In real-world engineering workflows, broken JSON originates from multiple sources: copy-pasting JavaScript object literals from console logs, exporting Python dictionaries, dealing with truncated LLM responses, or editing configuration files by hand where trailing commas are inadvertently left behind.
JSONGlow's JSON Repair engine implements a resilient tokenizer and recursive descent parser that understands relaxed JSON grammars. It converts single quotes to strict double quotes, quotes bareword identifiers, strips single-line and multi-line comments, drops trailing commas, inserts missing array separators, and converts language-specific primitives (`None`, `undefined`, `NaN`) to valid JSON counterparts.
All repair processing executes purely in your local browser runtime. Sensitive API responses, credentials, and database fixtures are never transmitted across the network, ensuring complete privacy and compliance.
Workflow Guide
How to use JSON Repair Online
Input malformed data
Paste invalid JSON, Python dictionaries, or JavaScript console logs containing trailing commas or single quotes into the editor.
Instant normalization
The repair engine detects syntax violations, fixes quotes, removes comments, and restores valid RFC 8259 syntax instantly.
Ready for production
Inspect the repaired output, format indentation to your preference, and click 'Copy' or 'Download .json' for immediate use.
Practical Demonstration
Malformed JSON Auto-Repair Example
Witness how single quotes, unquoted keys, comments, Python literals, and trailing commas are effortlessly repaired.
{
// User Profile Data
name: 'Alex Rivera',
age: 29,
is_admin: True,
tags: ['developer', 'sysadmin',],
settings: {
theme: 'dark',
notifications: None,
},
}{
"name": "Alex Rivera",
"age": 29,
"is_admin": true,
"tags": [
"developer",
"sysadmin"
],
"settings": {
"theme": "dark",
"notifications": null
}
}Troubleshooting & Edge Cases
Common syntax errors & how to avoid them
Trailing commas in arrays and objects
Why it happens: Extra commas left at the end of lists or dictionary blocks cause `SyntaxError: Unexpected token , in JSON`.
Python dictionary literals (True, False, None)
Why it happens: Python `str(dict)` outputs capitalized booleans and `None`, which are invalid tokens in standard JSON.
Unquoted or single-quoted keys and values
Why it happens: JavaScript object syntax allows `{ foo: 'bar' }`, which crashes strict JSON parsers.
Embedded JavaScript / C-style comments
Why it happens: `//` single line comments and `/* */` block comments are rejected by standard JSON parsers.
Core Capabilities
Engineered for speed & precision
Fix Trailing & Missing Commas
Prunes illegal trailing commas in objects/arrays and inserts missing separators between elements.
Quote Normalization
Converts single-quoted strings and unquoted JavaScript identifiers into standard double-quoted keys.
Python Literal Support
Automatically converts Python `True`, `False`, and `None` into valid JSON equivalents.
Comment Stripping
Removes `//` single-line and `/* */` multi-line comments cleanly without corrupting string contents.
Unescaped Character Repair
Repairs unescaped quotes, special characters, and raw newlines within string literals.
100% Private & In-Browser
All repair logic executes locally in your browser sandbox without network transmissions.
Frequently Asked Questions
Common questions answered.
Need more help? Our tools execute entirely in your browser without transmitting any payload to remote servers.
How does JSON Repair fix trailing commas and unquoted keys?+
JSON Repair uses a specialized resilient tokenizer that tolerates relaxed grammar rules. It recognizes trailing commas, unquoted keys, and single quotes, reconstructing a canonical JSON Abstract Syntax Tree.
Can I repair Python dictionary string outputs?+
Yes! Paste outputs from Python `str(dict)` containing `True`, `False`, `None`, and single quotes. The tool normalizes them into compliant JSON.
Can JSON Repair fix truncated JSON from LLMs like ChatGPT or Claude?+
Yes. Incomplete JSON with missing closing brackets or braces (`}`, `]`) is automatically balanced and closed by the repair engine.
Is my data uploaded to any server for repair?+
No. All repair processing is strictly executed within your client-side browser instance.
What should I do after repairing my JSON?+
You can format it with custom indentation, validate it, convert it to TypeScript interfaces or Zod schemas, or compare it against other payloads using JSONGlow's integrated toolset.
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