Why Your JSON Keeps Breaking (And How to Fix It Fast)

You paste a JSON config into your app and hit SyntaxError: Unexpected token . You scan 60 lines of curly braces, counting quotes by eye. Five minutes later you spot it — a trailing comma on line 47. Sound familiar? JSON is ruthlessly strict. No trailing commas. No comments. No single quotes. No unquoted keys. Even one character out of place produces a completely opaque error message that points you to the wrong line half the time. This post covers the four JSON mistakes that cause 90% of parse f