What are the most common JSON formatting errors?
The most common JSON errors include trailing commas, single quotes instead of double quotes, missing quotes around keys, and mismatched brackets or braces. Because JSON is a strict standard, any syntax deviation will cause a parser error in your application.
The Trailing Comma Trap
In many programming languages (like JavaScript or PHP), a trailing comma in an array is fine. In JSON, it is a fatal error. I always use a JSON validator before deployment because it catches these invisible bugs that manual code review often misses.
Quotes Matter
I frequently see developers using single quotes (') in JSON objects. **JSON requires double quotes (") for both keys and string values.** This is a non-negotiable part of the RFC 8259 spec. If you are getting a "Unexpected token" error, check your quotes first.
