Top 7 Common JSON Syntax Errors & How to Fix Them

1. Trailing Commas

The Error: Adding a comma after the final property in an object or element in an array.

// INVALID:
{
  "name": "ToolNest",
  "version": 1.0,
}

// FIXED:
{
  "name": "ToolNest",
  "version": 1.0
}

2. Single Quotes Instead of Double Quotes

The Error: Using single quotes (') for strings or keys.

// INVALID:
{'status': 'success'}

// FIXED:
{"status": "success"}

3. Comments Inside JSON

Standard RFC 8259 JSON does not support comments. If your configuration requires comments, consider JSONC (JSON with Comments) or YAML.

4. Unescaped Control Characters

Raw unescaped newline characters inside string literals will break the parser. Always use \n inside JSON strings.