Fix broken JSON with automatic fault-tolerant repair.
Auto-correct single quotes, unquoted keys, trailing commas, missing commas, JavaScript/Python literals (True/False/None), and comments instantly in local memory.
{
"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 uses a fault-tolerant AST parser to automatically detect and remediate invalid JSON syntax directly in your browser without cloud uploads.
Overview
Automated remediation for real-world malformed JSON
Real-world data ingestion pipelines frequently encounter malformed JSON produced by third-party APIs, legacy export scripts, Python dictionaries, or hand-edited configuration files. A single misplaced trailing comma or unquoted key causes standard JSON parsers to abort with an unhelpful SyntaxError.
Instead of manually inspecting thousands of lines to find a missing comma or quotation mark, JSONGlow's Repair engine employs a lenient state-machine parser. It identifies syntax flaws, applies RFC-compliant corrections, and outputs clean JSON ready for our JSON Formatter or validation in the JSON Validator.
The repair engine resolves common JavaScript object literal formats (unquoted keys, single-quoted strings), Python literals (True, False, None), C-style block comments (/* */), single-line comments (//), and trailing commas without mutating the underlying data values.
All processing runs client-side inside your web browser sandbox. Whether repairing proprietary server logs, credentials, or customer payloads, your data is never uploaded to any remote server. For specialized error explanations, check out our guide on Fixing Trailing Commas in JSON or troubleshooting Unexpected Token in JSON.
Workflow Guide
How to use JSON Repair Online
Input your malformed payload
Paste invalid JSON, Python dictionaries, or unquoted configuration data into the left editor panel.
Instant AST-level repair
The fault-tolerant parser automatically detects syntax errors and fixes quotes, commas, and literals in real time.
Copy or download valid JSON
Click 'Copy' to copy the corrected RFC-compliant JSON to your clipboard or download it directly.
Practical Demonstration
Broken JSON Auto-Repair
See how single quotes, comments, and unquoted keys are automatically transformed into valid JSON.
// Config with JavaScript literal syntax:
{
name: 'JSONGlow Repair',
enabled: True,
items: [
"parser",
"ast", // trailing comma
],
}{
"name": "JSONGlow Repair",
"enabled": true,
"items": [
"parser",
"ast"
]
}Troubleshooting & Edge Cases
Common syntax errors & how to avoid them
Single quotes instead of double quotes
Why it happens: JavaScript and Python allow single-quoted strings, but RFC 8259 strictly requires double quotes.
// Broken: {'status': 'ok'}
// Fixed: {"status": "ok"}Unquoted object keys
Why it happens: JavaScript object shorthand allows unquoted keys, which fails strict JSON parsing.
// Broken: {id: 101}
// Fixed: {"id": 101}Trailing commas in arrays or objects
Why it happens: Commas following the last item in a list or object violate standard JSON grammar.
Python boolean & null literals
Why it happens: Python exports often include True, False, or None, which break standard JSON parsers.
Core Capabilities
Engineered for speed & precision
Fault-Tolerant AST Parser
Lenient parsing recovers data from severely corrupted JSON structures without losing nested hierarchy.
Python & JS Literal Support
Automatically converts Python True/False/None and JS unquoted keys into strict JSON equivalents.
Comment Stripping
Safely strips single-line (//) and multi-line (/* */) comments without affecting string contents.
100% In-Browser Privacy
Zero server uploads. Your proprietary code and credentials are repaired locally on your machine.
Change Highlighting
Visual notification alerts you whenever modifications are made during the repair cycle.
One-Click Export
Download the repaired file or copy it directly to your clipboard in standard 2-space indentation.
Frequently Asked Questions
Common questions answered.
Need more help? Our tools execute entirely in your browser without transmitting any payload to remote servers.
What types of JSON errors can this tool automatically fix?+
JSONGlow repairs single quotes, unquoted keys, trailing commas, missing commas between properties, C/C++ style comments, Python literals (True/False/None), and unescaped line breaks.
Does repairing modify the underlying data values?+
No. The engine strictly repairs structural syntax tokens (quotes, commas, brackets) while preserving exact string contents, numbers, and boolean values.
Is my data uploaded to any remote server?+
No. The entire repair algorithm runs locally in JavaScript inside your browser sandbox. No network calls are made with your data.
Can this tool fix truncated JSON files?+
Yes. If a JSON payload was cut short by an API timeout or buffer limit, the repair engine attempts to automatically close open arrays and objects.
Is this repair tool free to use?+
Yes. JSONGlow JSON Repair is 100% free with no limits, no login required, and no advertisements.
Explore More Tools & Guides
The JSONGlow developer kit.
JSON Formatter
Format, beautify, indent, sort keys alphabetically, and inspect nested JSON structures.
Unexpected Token in JSON
Troubleshoot and fix 'Unexpected token in JSON' caused by single quotes, HTML error responses, or trailing commas.
JSON Validator
Live strict RFC 8259 syntax checker pointing to exact line and column coordinates of malformed tokens.