JSON Repair

Related

What is JSON Repair?

Use Cases

• AI/LLM output cleanup: one-click convert Markdown-wrapped, explanatory-text-augmented and trailing-comma-laden JSON returned by ChatGPT/Claude into standard JSON
• Interface debugging and troubleshooting: when API responses are truncated by gateway or network issues, quickly complete brackets and strings to locate the original data structure
• JavaScript object literals copied from console: one-stop fix for single quotes, trailing commas, and unquoted keys
• Configuration file cleaning: strip comments from JSON5/JSONC to obtain standard JSON, ready for unified downstream consumption
• Log & clipboard data repair: quickly standardize JSON snippets containing comments, special whitespace, or truncation
• Data migration & script pre-processing: add a repair step in the data migration pipeline to prevent a few invalid JSONs from blocking an entire ETL batch

How to Use

1. Paste the error-containing, Markdown-wrapped, or truncated JSON content into the left input box, or click "Sample" to load a typical broken JSON, or upload a .json/.txt file
2. The tool automatically detects and fixes common syntax issues; the right output area shows the formatted standard JSON and the count of each class of problem repaired
3. If red error messages remain, you can manually edit the input and re-trigger repair (Mac: ⌘+Shift+R, Windows: Ctrl+Shift+R)
4. After confirming the structure is correct, click "Copy" to put the repaired result in the clipboard, or click "Download" to save as repaired.json for further formatting, validation, etc.

Features

• Covers 7 common syntax errors: trailing commas, single quotes, unquoted keys, unclosed strings, comments, missing brackets, Markdown code block wrappers
• AI output cleanup optimized: auto-strip ```json wrappers and surrounding explanatory text; recognizes typical output from ChatGPT, Claude, Gemini and other LLMs
• JSON5/JSONC compatible: parses extended syntax including comments, loose quotes, and special whitespace (e.g. invisible Unicode characters)
• Truncated JSON smart completion: handles truncated API responses and missing closing braces by auto-completing missing brackets and quotes
• Repair problem visualization: auto-stats and shows the count of each class of problem repaired for easy audit and human review
• Local processing for privacy: parsing, repair, and formatting all happen locally in the browser, no input sent to any server
• Seamless hand-off to formatting: repaired standard JSON can directly enter JSON Formatter, Schema Validator, or code generator as next steps
• File & sample loading: supports uploading .json/.txt files or clicking to load a sample for quick verification of repair effects

Code Examples

// npm install jsonrepair
import { jsonrepair } from 'jsonrepair';

const broken = `{
  name: 'Alice',
  age: 30,
  tags: ['dev', 'writer',], // trailing comma + comment
}`;

try {
  const fixed = jsonrepair(broken);
  const obj = JSON.parse(fixed);
  console.log(obj);
  // => { name: 'Alice', age: 30, tags: ['dev', 'writer'] }
} catch (err) {
  console.error('Still unrepairable:', err.message);
}

# pip install jsonrepair
from jsonrepair import jsonrepair
import json

broken = '''{
  name: "Alice",
  age: 30,
  tags: ["dev", "writer",], // trailing comma + comment
}'''

fixed = jsonrepair(broken)
obj = json.loads(fixed)
print(obj)
# => {'name': 'Alice', 'age': 30, 'tags': ['dev', 'writer']}

# Strip trailing commas from objects/arrays (emergency option; does NOT handle comments / single quotes)
# For complex scenarios, use a dedicated library like jsonrepair
sed -E 's/,([ \t]*[}\]])/\1/g' broken.json > clean.json

# Validate the cleaned output
jq . clean.json >/dev/null && echo 'JSON is valid'

FAQ

Troubleshooting

Glossary

JSON

JavaScript Object Notation, a lightweight key-value based data interchange format defined in RFC 8259. De-facto standard for REST APIs, configuration files, and logs.

RFC 8259

The IETF official JSON specification, defining the strict syntax for valid JSON — all keys must be double-quoted, only a limited set of characters in strings need escaping, comments and trailing commas are not allowed.

JSON.parse

The strict JSON parser built into JavaScript and modern browsers, following RFC 8259. It throws SyntaxError on any syntax error and cannot perform tolerant repair.

JSON5

An extended syntax for JSON (non-standard), allowing unquoted keys, single-quoted strings, comments (// and /* */), trailing commas, hexadecimal numbers, etc. Easier for humans to write but incompatible with JSON.parse.

JSONC

JSON with Comments, a generic name used by editors like VS Code for JSON config files with comments (e.g. tsconfig.json). Effectively an alias for JSON5.

Trailing Comma

An extra comma after the last element of an object or array. Allowed in JavaScript but prohibited by JSON standard — the most common syntax error from LLM output and console.log() copies.

Markdown Code Block

A code snippet wrapped in three backticks (```). LLMs often auto-wrap JSON output in ```json ... ```; pasting directly to JSON.parse() will fail.

Tolerant Parser

A parser that attempts to recover and continue parsing when encountering syntax errors. The core engine of a JSON Repair tool, distinct from strict JSON.parse.

SyntaxError

The syntax error exception thrown by JavaScript. Any strict JSON parser throws this when receiving input that doesn't conform to RFC 8259.

Canonical JSON

JSON regenerated via parse + stringify, with stable key order, no extra whitespace, and 100% compatibility with standard parsers. The final output format of a JSON Repair tool.

Common JSON Repair Error Types with Examples

JSON Repair vs JSON Formatter vs JSON Schema Validation

Authoritative References

• IETFJSON Specification (RFC 8259)
• MDNJSON.parse - MDN Web Docs
• JSON5JSON5 - Unofficial extended syntax spec
• GitHubjsonrepair (josdejong) - Reference implementation for browser & Node